libavformat/spdifenc.c - nest-android-app/ffmpeg - Git at Google

 /*
  * IEC 61937 muxer
  * Copyright (c) 2009 Bartlomiej Wolowiec
  * Copyright (c) 2010 Anssi Hannula
  * Copyright (c) 2010 Carl Eugen Hoyos
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 /**
  * @file
  * IEC-61937 encapsulation of various formats, used by S/PDIF
  * @author Bartlomiej Wolowiec
  * @author Anssi Hannula
  * @author Carl Eugen Hoyos
  */

 /*
  * Terminology used in specification:
  * data-burst - IEC61937 frame, contains header and encapsuled frame
  * burst-preambule - IEC61937 frame header, contains 16-bits words named Pa, Pb, Pc and Pd
  * burst-payload - encapsuled frame
  * Pa, Pb - syncword - 0xF872, 0x4E1F
  * Pc - burst-info, contains data-type (bits 0-6), error flag (bit 7), data-type-dependent info (bits 8-12)
  *      and bitstream number (bits 13-15)
  * data-type - determines type of encapsuled frames
  * Pd - length code (number of bits or bytes of encapsuled frame - according to data_type)
  *
  * IEC 61937 frames at normal usage start every specific count of bytes,
  *      dependent from data-type (spaces between packets are filled by zeros)
  */

 #include <inttypes.h>

 #include "avformat.h"
 #include "avio_internal.h"
 #include "spdif.h"
 #include "libavcodec/ac3.h"
 #include "libavcodec/dca.h"
 #include "libavcodec/dca_syncwords.h"
 #include "libavcodec/aacadtsdec.h"
 #include "libavutil/opt.h"

 typedef struct IEC61937Context {
     const AVClass *av_class;
     enum IEC61937DataType data_type;///< burst info - reference to type of payload of the data-burst
     int length_code;                ///< length code in bits or bytes, depending on data type
     int pkt_offset;                 ///< data burst repetition period in bytes
     uint8_t *buffer;                ///< allocated buffer, used for swap bytes
     int buffer_size;                ///< size of allocated buffer

     uint8_t *out_buf;               ///< pointer to the outgoing data before byte-swapping
     int out_bytes;                  ///< amount of outgoing bytes

     int use_preamble;               ///< preamble enabled (disabled for exactly pre-padded DTS)
     int extra_bswap;                ///< extra bswap for payload (for LE DTS => standard BE DTS)

     uint8_t *hd_buf;                ///< allocated buffer to concatenate hd audio frames
     int hd_buf_size;                ///< size of the hd audio buffer
     int hd_buf_count;               ///< number of frames in the hd audio buffer
     int hd_buf_filled;              ///< amount of bytes in the hd audio buffer

     int dtshd_skip;                 ///< counter used for skipping DTS-HD frames

     /* AVOptions: */
     int dtshd_rate;
     int dtshd_fallback;
 #define SPDIF_FLAG_BIGENDIAN    0x01
     int spdif_flags;

     /// function, which generates codec dependent header information.
     /// Sets data_type and pkt_offset, and length_code, out_bytes, out_buf if necessary
     int (*header_info) (AVFormatContext *s, AVPacket *pkt);
 } IEC61937Context;

 static const AVOption options[] = {
 { "spdif_flags", "IEC 61937 encapsulation flags", offsetof(IEC61937Context, spdif_flags), AV_OPT_TYPE_FLAGS, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "spdif_flags" },
 { "be", "output in big-endian format (for use as s16be)", 0, AV_OPT_TYPE_CONST, {.i64 = SPDIF_FLAG_BIGENDIAN},  0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "spdif_flags" },
 { "dtshd_rate", "mux complete DTS frames in HD mode at the specified IEC958 rate (in Hz, default 0=disabled)", offsetof(IEC61937Context, dtshd_rate), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 768000, AV_OPT_FLAG_ENCODING_PARAM },
 { "dtshd_fallback_time", "min secs to strip HD for after an overflow (-1: till the end, default 60)", offsetof(IEC61937Context, dtshd_fallback), AV_OPT_TYPE_INT, {.i64 = 60}, -1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
 { NULL },
 };

 static const AVClass spdif_class = {
     .class_name     = "spdif",
     .item_name      = av_default_item_name,
     .option         = options,
     .version        = LIBAVUTIL_VERSION_INT,
 };

 static int spdif_header_ac3(AVFormatContext *s, AVPacket *pkt)
 {
     IEC61937Context *ctx = s->priv_data;
     int bitstream_mode = pkt->data[5] & 0x7;

     ctx->data_type  = IEC61937_AC3 | (bitstream_mode << 8);
     ctx->pkt_offset = AC3_FRAME_SIZE << 2;
     return 0;
 }

 static int spdif_header_eac3(AVFormatContext *s, AVPacket *pkt)
 {
     IEC61937Context *ctx = s->priv_data;
     static const uint8_t eac3_repeat[4] = {6, 3, 2, 1};
     int repeat = 1;

     if ((pkt->data[4] & 0xc0) != 0xc0) /* fscod */
         repeat = eac3_repeat[(pkt->data[4] & 0x30) >> 4]; /* numblkscod */

     ctx->hd_buf = av_fast_realloc(ctx->hd_buf, &ctx->hd_buf_size, ctx->hd_buf_filled + pkt->size);
     if (!ctx->hd_buf)
         return AVERROR(ENOMEM);

     memcpy(&ctx->hd_buf[ctx->hd_buf_filled], pkt->data, pkt->size);

     ctx->hd_buf_filled += pkt->size;
     if (++ctx->hd_buf_count < repeat){
         ctx->pkt_offset = 0;
         return 0;
     }
     ctx->data_type   = IEC61937_EAC3;
     ctx->pkt_offset  = 24576;
     ctx->out_buf     = ctx->hd_buf;
     ctx->out_bytes   = ctx->hd_buf_filled;
     ctx->length_code = ctx->hd_buf_filled;

     ctx->hd_buf_count  = 0;
     ctx->hd_buf_filled = 0;
     return 0;
 }

 /*
  * DTS type IV (DTS-HD) can be transmitted with various frame repetition
  * periods; longer repetition periods allow for longer packets and therefore
  * higher bitrate. Longer repetition periods mean that the constant bitrate of
  * the outputted IEC 61937 stream is higher.
  * The repetition period is measured in IEC 60958 frames (4 bytes).
  */
 static int spdif_dts4_subtype(int period)
 {
     switch (period) {
     case 512:   return 0x0;
     case 1024:  return 0x1;
     case 2048:  return 0x2;
     case 4096:  return 0x3;
     case 8192:  return 0x4;
     case 16384: return 0x5;
     }
     return -1;
 }

 static int spdif_header_dts4(AVFormatContext *s, AVPacket *pkt, int core_size,
                              int sample_rate, int blocks)
 {
     IEC61937Context *ctx = s->priv_data;
     static const char dtshd_start_code[10] = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfe, 0xfe };
     int pkt_size = pkt->size;
     int period;
     int subtype;

     if (!core_size) {
         av_log(s, AV_LOG_ERROR, "HD mode not supported for this format\n");
         return AVERROR(EINVAL);
     }

     if (!sample_rate) {
         av_log(s, AV_LOG_ERROR, "Unknown DTS sample rate for HD\n");
         return AVERROR_INVALIDDATA;
     }

     period = ctx->dtshd_rate * (blocks << 5) / sample_rate;
     subtype = spdif_dts4_subtype(period);

     if (subtype < 0) {
         av_log(s, AV_LOG_ERROR, "Specified HD rate of %d Hz would require an "
                "impossible repetition period of %d for the current DTS stream"
                " (blocks = %d, sample rate = %d)\n", ctx->dtshd_rate, period,
                blocks << 5, sample_rate);
         return AVERROR(EINVAL);
     }

     /* set pkt_offset and DTS IV subtype according to the requested output
      * rate */
     ctx->pkt_offset = period * 4;
     ctx->data_type = IEC61937_DTSHD | subtype << 8;

     /* If the bitrate is too high for transmitting at the selected
      * repetition period setting, strip DTS-HD until a good amount
      * of consecutive non-overflowing HD frames have been observed.
      * This generally only happens if the caller is cramming a Master
      * Audio stream into 192kHz IEC 60958 (which may or may not fit). */
     if (sizeof(dtshd_start_code) + 2 + pkt_size
             > ctx->pkt_offset - BURST_HEADER_SIZE && core_size) {
         if (!ctx->dtshd_skip)
             av_log(s, AV_LOG_WARNING, "DTS-HD bitrate too high, "
                                       "temporarily sending core only\n");
         if (ctx->dtshd_fallback > 0)
             ctx->dtshd_skip = sample_rate * ctx->dtshd_fallback / (blocks << 5);
         else
             /* skip permanently (dtshd_fallback == -1) or just once
              * (dtshd_fallback == 0) */
             ctx->dtshd_skip = 1;
     }
     if (ctx->dtshd_skip && core_size) {
         pkt_size = core_size;
         if (ctx->dtshd_fallback >= 0)
             --ctx->dtshd_skip;
     }

     ctx->out_bytes   = sizeof(dtshd_start_code) + 2 + pkt_size;

     /* Align so that (length_code & 0xf) == 0x8. This is reportedly needed
      * with some receivers, but the exact requirement is unconfirmed. */
     ctx->length_code = FFALIGN(ctx->out_bytes + 0x8, 0x10) - 0x8;

     av_fast_malloc(&ctx->hd_buf, &ctx->hd_buf_size, ctx->out_bytes);
     if (!ctx->hd_buf)
         return AVERROR(ENOMEM);

     ctx->out_buf = ctx->hd_buf;

     memcpy(ctx->hd_buf, dtshd_start_code, sizeof(dtshd_start_code));
     AV_WB16(ctx->hd_buf + sizeof(dtshd_start_code), pkt_size);
     memcpy(ctx->hd_buf + sizeof(dtshd_start_code) + 2, pkt->data, pkt_size);

     return 0;
 }

 static int spdif_header_dts(AVFormatContext *s, AVPacket *pkt)
 {
     IEC61937Context *ctx = s->priv_data;
     uint32_t syncword_dts = AV_RB32(pkt->data);
     int blocks;
     int sample_rate = 0;
     int core_size = 0;

     if (pkt->size < 9)
         return AVERROR_INVALIDDATA;

     switch (syncword_dts) {
     case DCA_SYNCWORD_CORE_BE:
         blocks = (AV_RB16(pkt->data + 4) >> 2) & 0x7f;
         core_size = ((AV_RB24(pkt->data + 5) >> 4) & 0x3fff) + 1;
         sample_rate = avpriv_dca_sample_rates[(pkt->data[8] >> 2) & 0x0f];
         break;
     case DCA_SYNCWORD_CORE_LE:
         blocks = (AV_RL16(pkt->data + 4) >> 2) & 0x7f;
         ctx->extra_bswap = 1;
         break;
     case DCA_SYNCWORD_CORE_14B_BE:
         blocks =
             (((pkt->data[5] & 0x07) << 4) | ((pkt->data[6] & 0x3f) >> 2));
         break;
     case DCA_SYNCWORD_CORE_14B_LE:
         blocks =
             (((pkt->data[4] & 0x07) << 4) | ((pkt->data[7] & 0x3f) >> 2));
         ctx->extra_bswap = 1;
         break;
     case DCA_SYNCWORD_SUBSTREAM:
         /* We only handle HD frames that are paired with core. However,
            sometimes DTS-HD streams with core have a stray HD frame without
            core in the beginning of the stream. */
         av_log(s, AV_LOG_ERROR, "stray DTS-HD frame\n");
         return AVERROR_INVALIDDATA;
     default:
         av_log(s, AV_LOG_ERROR, "bad DTS syncword 0x%"PRIx32"\n", syncword_dts);
         return AVERROR_INVALIDDATA;
     }
     blocks++;

     if (ctx->dtshd_rate)
         /* DTS type IV output requested */
         return spdif_header_dts4(s, pkt, core_size, sample_rate, blocks);

     switch (blocks) {
     case  512 >> 5: ctx->data_type = IEC61937_DTS1; break;
     case 1024 >> 5: ctx->data_type = IEC61937_DTS2; break;
     case 2048 >> 5: ctx->data_type = IEC61937_DTS3; break;
     default:
         av_log(s, AV_LOG_ERROR, "%i samples in DTS frame not supported\n",
                blocks << 5);
         return AVERROR(ENOSYS);
     }

     /* discard extraneous data by default */
     if (core_size && core_size < pkt->size) {
         ctx->out_bytes = core_size;
         ctx->length_code = core_size << 3;
     }

     ctx->pkt_offset = blocks << 7;

     if (ctx->out_bytes == ctx->pkt_offset) {
         /* The DTS stream fits exactly into the output stream, so skip the
          * preamble as it would not fit in there. This is the case for dts
          * discs and dts-in-wav. */
         ctx->use_preamble = 0;
     } else if (ctx->out_bytes > ctx->pkt_offset - BURST_HEADER_SIZE) {
         avpriv_request_sample(s, "Unrecognized large DTS frame");
         /* This will fail with a "bitrate too high" in the caller */
     }

     return 0;
 }

 static const enum IEC61937DataType mpeg_data_type[2][3] = {
     //     LAYER1                      LAYER2                  LAYER3
     { IEC61937_MPEG2_LAYER1_LSF, IEC61937_MPEG2_LAYER2_LSF, IEC61937_MPEG2_LAYER3_LSF },//MPEG2 LSF
     { IEC61937_MPEG1_LAYER1,     IEC61937_MPEG1_LAYER23,    IEC61937_MPEG1_LAYER23 },   //MPEG1
 };

 static int spdif_header_mpeg(AVFormatContext *s, AVPacket *pkt)
 {
     IEC61937Context *ctx = s->priv_data;
     int version =      (pkt->data[1] >> 3) & 3;
     int layer   = 3 - ((pkt->data[1] >> 1) & 3);
     int extension = pkt->data[2] & 1;

     if (layer == 3 || version == 1) {
         av_log(s, AV_LOG_ERROR, "Wrong MPEG file format\n");
         return AVERROR_INVALIDDATA;
     }
     av_log(s, AV_LOG_DEBUG, "version: %i layer: %i extension: %i\n", version, layer, extension);
     if (version == 2 && extension) {
         ctx->data_type  = IEC61937_MPEG2_EXT;
         ctx->pkt_offset = 4608;
     } else {
         ctx->data_type  = mpeg_data_type [version & 1][layer];
         ctx->pkt_offset = spdif_mpeg_pkt_offset[version & 1][layer];
     }
     // TODO Data type dependent info (normal/karaoke, dynamic range control)
     return 0;
 }

 static int spdif_header_aac(AVFormatContext *s, AVPacket *pkt)
 {
     IEC61937Context *ctx = s->priv_data;
     AACADTSHeaderInfo hdr;
     GetBitContext gbc;
     int ret;

     init_get_bits(&gbc, pkt->data, AAC_ADTS_HEADER_SIZE * 8);
     ret = avpriv_aac_parse_header(&gbc, &hdr);
     if (ret < 0) {
         av_log(s, AV_LOG_ERROR, "Wrong AAC file format\n");
         return AVERROR_INVALIDDATA;
     }

     ctx->pkt_offset = hdr.samples << 2;
     switch (hdr.num_aac_frames) {
     case 1:
         ctx->data_type = IEC61937_MPEG2_AAC;
         break;
     case 2:
         ctx->data_type = IEC61937_MPEG2_AAC_LSF_2048;
         break;
     case 4:
         ctx->data_type = IEC61937_MPEG2_AAC_LSF_4096;
         break;
     default:
         av_log(s, AV_LOG_ERROR,
                "%"PRIu32" samples in AAC frame not supported\n", hdr.samples);
         return AVERROR(EINVAL);
     }
     //TODO Data type dependent info (LC profile/SBR)
     return 0;
 }


 /*
  * It seems Dolby TrueHD frames have to be encapsulated in MAT frames before
  * they can be encapsulated in IEC 61937.
  * Here we encapsulate 24 TrueHD frames in a single MAT frame, padding them
  * to achieve constant rate.
  * The actual format of a MAT frame is unknown, but the below seems to work.
  * However, it seems it is not actually necessary for the 24 TrueHD frames to
  * be in an exact alignment with the MAT frame.
  */
 #define MAT_FRAME_SIZE          61424
 #define TRUEHD_FRAME_OFFSET     2560
 #define MAT_MIDDLE_CODE_OFFSET  -4

 static int spdif_header_truehd(AVFormatContext *s, AVPacket *pkt)
 {
     IEC61937Context *ctx = s->priv_data;
     int mat_code_length = 0;
     static const char mat_end_code[16] = { 0xC3, 0xC2, 0xC0, 0xC4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x97, 0x11 };

     if (!ctx->hd_buf_count) {
         static const char mat_start_code[20] = { 0x07, 0x9E, 0x00, 0x03, 0x84, 0x01, 0x01, 0x01, 0x80, 0x00, 0x56, 0xA5, 0x3B, 0xF4, 0x81, 0x83, 0x49, 0x80, 0x77, 0xE0 };
         mat_code_length = sizeof(mat_start_code) + BURST_HEADER_SIZE;
         memcpy(ctx->hd_buf, mat_start_code, sizeof(mat_start_code));

     } else if (ctx->hd_buf_count == 12) {
         static const char mat_middle_code[12] = { 0xC3, 0xC1, 0x42, 0x49, 0x3B, 0xFA, 0x82, 0x83, 0x49, 0x80, 0x77, 0xE0 };
         mat_code_length = sizeof(mat_middle_code) + MAT_MIDDLE_CODE_OFFSET;
         memcpy(&ctx->hd_buf[12 * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + MAT_MIDDLE_CODE_OFFSET],
                mat_middle_code, sizeof(mat_middle_code));
     }

     if (pkt->size > TRUEHD_FRAME_OFFSET - mat_code_length) {
         /* if such frames exist, we'd need some more complex logic to
          * distribute the TrueHD frames in the MAT frame */
         avpriv_request_sample(s, "Too large TrueHD frame of %d bytes",
                               pkt->size);
         return AVERROR_PATCHWELCOME;
     }

     memcpy(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length],
            pkt->data, pkt->size);
     memset(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length + pkt->size],
            0, TRUEHD_FRAME_OFFSET - pkt->size - mat_code_length);

     if (++ctx->hd_buf_count < 24){
         ctx->pkt_offset = 0;
         return 0;
     }
     memcpy(&ctx->hd_buf[MAT_FRAME_SIZE - sizeof(mat_end_code)], mat_end_code, sizeof(mat_end_code));
     ctx->hd_buf_count = 0;

     ctx->data_type   = IEC61937_TRUEHD;
     ctx->pkt_offset  = 61440;
     ctx->out_buf     = ctx->hd_buf;
     ctx->out_bytes   = MAT_FRAME_SIZE;
     ctx->length_code = MAT_FRAME_SIZE;
     return 0;
 }

 static int spdif_write_header(AVFormatContext *s)
 {
     IEC61937Context *ctx = s->priv_data;

     switch (s->streams[0]->codec->codec_id) {
     case AV_CODEC_ID_AC3:
         ctx->header_info = spdif_header_ac3;
         break;
     case AV_CODEC_ID_EAC3:
         ctx->header_info = spdif_header_eac3;
         break;
     case AV_CODEC_ID_MP1:
     case AV_CODEC_ID_MP2:
     case AV_CODEC_ID_MP3:
         ctx->header_info = spdif_header_mpeg;
         break;
     case AV_CODEC_ID_DTS:
         ctx->header_info = spdif_header_dts;
         break;
     case AV_CODEC_ID_AAC:
         ctx->header_info = spdif_header_aac;
         break;
     case AV_CODEC_ID_TRUEHD:
     case AV_CODEC_ID_MLP:
         ctx->header_info = spdif_header_truehd;
         ctx->hd_buf = av_malloc(MAT_FRAME_SIZE);
         if (!ctx->hd_buf)
             return AVERROR(ENOMEM);
         break;
     default:
         av_log(s, AV_LOG_ERROR, "codec not supported\n");
         return AVERROR_PATCHWELCOME;
     }
     return 0;
 }

 static int spdif_write_trailer(AVFormatContext *s)
 {
     IEC61937Context *ctx = s->priv_data;
     av_freep(&ctx->buffer);
     av_freep(&ctx->hd_buf);
     return 0;
 }

 static av_always_inline void spdif_put_16(IEC61937Context *ctx,
                                           AVIOContext *pb, unsigned int val)
 {
     if (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)
         avio_wb16(pb, val);
     else
         avio_wl16(pb, val);
 }

 static int spdif_write_packet(struct AVFormatContext *s, AVPacket *pkt)
 {
     IEC61937Context *ctx = s->priv_data;
     int ret, padding;

     ctx->out_buf = pkt->data;
     ctx->out_bytes = pkt->size;
     ctx->length_code = FFALIGN(pkt->size, 2) << 3;
     ctx->use_preamble = 1;
     ctx->extra_bswap = 0;

     ret = ctx->header_info(s, pkt);
     if (ret < 0)
         return ret;
     if (!ctx->pkt_offset)
         return 0;

     padding = (ctx->pkt_offset - ctx->use_preamble * BURST_HEADER_SIZE - ctx->out_bytes) & ~1;
     if (padding < 0) {
         av_log(s, AV_LOG_ERROR, "bitrate is too high\n");
         return AVERROR(EINVAL);
     }

     if (ctx->use_preamble) {
         spdif_put_16(ctx, s->pb, SYNCWORD1);       //Pa
         spdif_put_16(ctx, s->pb, SYNCWORD2);       //Pb
         spdif_put_16(ctx, s->pb, ctx->data_type);  //Pc
         spdif_put_16(ctx, s->pb, ctx->length_code);//Pd
     }

     if (ctx->extra_bswap ^ (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)) {
         avio_write(s->pb, ctx->out_buf, ctx->out_bytes & ~1);
     } else {
         av_fast_malloc(&ctx->buffer, &ctx->buffer_size, ctx->out_bytes + AV_INPUT_BUFFER_PADDING_SIZE);
         if (!ctx->buffer)
             return AVERROR(ENOMEM);
         ff_spdif_bswap_buf16((uint16_t *)ctx->buffer, (uint16_t *)ctx->out_buf, ctx->out_bytes >> 1);
         avio_write(s->pb, ctx->buffer, ctx->out_bytes & ~1);
     }

     /* a final lone byte has to be MSB aligned */
     if (ctx->out_bytes & 1)
         spdif_put_16(ctx, s->pb, ctx->out_buf[ctx->out_bytes - 1] << 8);

     ffio_fill(s->pb, 0, padding);

     av_log(s, AV_LOG_DEBUG, "type=%x len=%i pkt_offset=%i\n",
            ctx->data_type, ctx->out_bytes, ctx->pkt_offset);

     return 0;
 }

 AVOutputFormat ff_spdif_muxer = {
     .name              = "spdif",
     .long_name         = NULL_IF_CONFIG_SMALL("IEC 61937 (used on S/PDIF - IEC958)"),
     .extensions        = "spdif",
     .priv_data_size    = sizeof(IEC61937Context),
     .audio_codec       = AV_CODEC_ID_AC3,
     .video_codec       = AV_CODEC_ID_NONE,
     .write_header      = spdif_write_header,
     .write_packet      = spdif_write_packet,
     .write_trailer     = spdif_write_trailer,
     .flags             = AVFMT_NOTIMESTAMPS,
     .priv_class        = &spdif_class,
 };
	/*
	* IEC 61937 muxer
	* Copyright (c) 2009 Bartlomiej Wolowiec
	* Copyright (c) 2010 Anssi Hannula
	* Copyright (c) 2010 Carl Eugen Hoyos
	*
	* This file is part of FFmpeg.
	*
	* FFmpeg is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* FFmpeg is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with FFmpeg; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	/**
	* @file
	* IEC-61937 encapsulation of various formats, used by S/PDIF
	* @author Bartlomiej Wolowiec
	* @author Anssi Hannula
	* @author Carl Eugen Hoyos
	*/

	/*
	* Terminology used in specification:
	* data-burst - IEC61937 frame, contains header and encapsuled frame
	* burst-preambule - IEC61937 frame header, contains 16-bits words named Pa, Pb, Pc and Pd
	* burst-payload - encapsuled frame
	* Pa, Pb - syncword - 0xF872, 0x4E1F
	* Pc - burst-info, contains data-type (bits 0-6), error flag (bit 7), data-type-dependent info (bits 8-12)
	* and bitstream number (bits 13-15)
	* data-type - determines type of encapsuled frames
	* Pd - length code (number of bits or bytes of encapsuled frame - according to data_type)
	*
	* IEC 61937 frames at normal usage start every specific count of bytes,
	* dependent from data-type (spaces between packets are filled by zeros)
	*/

	#include <inttypes.h>

	#include "avformat.h"
	#include "avio_internal.h"
	#include "spdif.h"
	#include "libavcodec/ac3.h"
	#include "libavcodec/dca.h"
	#include "libavcodec/dca_syncwords.h"
	#include "libavcodec/aacadtsdec.h"
	#include "libavutil/opt.h"

	typedef struct IEC61937Context {
	const AVClass *av_class;
	enum IEC61937DataType data_type;///< burst info - reference to type of payload of the data-burst
	int length_code; ///< length code in bits or bytes, depending on data type
	int pkt_offset; ///< data burst repetition period in bytes
	uint8_t *buffer; ///< allocated buffer, used for swap bytes
	int buffer_size; ///< size of allocated buffer

	uint8_t *out_buf; ///< pointer to the outgoing data before byte-swapping
	int out_bytes; ///< amount of outgoing bytes

	int use_preamble; ///< preamble enabled (disabled for exactly pre-padded DTS)
	int extra_bswap; ///< extra bswap for payload (for LE DTS => standard BE DTS)

	uint8_t *hd_buf; ///< allocated buffer to concatenate hd audio frames
	int hd_buf_size; ///< size of the hd audio buffer
	int hd_buf_count; ///< number of frames in the hd audio buffer
	int hd_buf_filled; ///< amount of bytes in the hd audio buffer

	int dtshd_skip; ///< counter used for skipping DTS-HD frames

	/* AVOptions: */
	int dtshd_rate;
	int dtshd_fallback;
	#define SPDIF_FLAG_BIGENDIAN 0x01
	int spdif_flags;

	/// function, which generates codec dependent header information.
	/// Sets data_type and pkt_offset, and length_code, out_bytes, out_buf if necessary
	int (header_info) (AVFormatContext s, AVPacket *pkt);
	} IEC61937Context;

	static const AVOption options[] = {
	{ "spdif_flags", "IEC 61937 encapsulation flags", offsetof(IEC61937Context, spdif_flags), AV_OPT_TYPE_FLAGS, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "spdif_flags" },
	{ "be", "output in big-endian format (for use as s16be)", 0, AV_OPT_TYPE_CONST, {.i64 = SPDIF_FLAG_BIGENDIAN}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "spdif_flags" },
	{ "dtshd_rate", "mux complete DTS frames in HD mode at the specified IEC958 rate (in Hz, default 0=disabled)", offsetof(IEC61937Context, dtshd_rate), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 768000, AV_OPT_FLAG_ENCODING_PARAM },
	{ "dtshd_fallback_time", "min secs to strip HD for after an overflow (-1: till the end, default 60)", offsetof(IEC61937Context, dtshd_fallback), AV_OPT_TYPE_INT, {.i64 = 60}, -1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
	{ NULL },
	};

	static const AVClass spdif_class = {
	.class_name = "spdif",
	.item_name = av_default_item_name,
	.option = options,
	.version = LIBAVUTIL_VERSION_INT,
	};

	static int spdif_header_ac3(AVFormatContext s, AVPacket pkt)
	{
	IEC61937Context *ctx = s->priv_data;
	int bitstream_mode = pkt->data[5] & 0x7;

	ctx->data_type = IEC61937_AC3 \| (bitstream_mode << 8);
	ctx->pkt_offset = AC3_FRAME_SIZE << 2;
	return 0;
	}

	static int spdif_header_eac3(AVFormatContext s, AVPacket pkt)
	{
	IEC61937Context *ctx = s->priv_data;
	static const uint8_t eac3_repeat[4] = {6, 3, 2, 1};
	int repeat = 1;

	if ((pkt->data[4] & 0xc0) != 0xc0) /* fscod */
	repeat = eac3_repeat[(pkt->data[4] & 0x30) >> 4]; /* numblkscod */

	ctx->hd_buf = av_fast_realloc(ctx->hd_buf, &ctx->hd_buf_size, ctx->hd_buf_filled + pkt->size);
	if (!ctx->hd_buf)
	return AVERROR(ENOMEM);

	memcpy(&ctx->hd_buf[ctx->hd_buf_filled], pkt->data, pkt->size);

	ctx->hd_buf_filled += pkt->size;
	if (++ctx->hd_buf_count < repeat){
	ctx->pkt_offset = 0;
	return 0;
	}
	ctx->data_type = IEC61937_EAC3;
	ctx->pkt_offset = 24576;
	ctx->out_buf = ctx->hd_buf;
	ctx->out_bytes = ctx->hd_buf_filled;
	ctx->length_code = ctx->hd_buf_filled;

	ctx->hd_buf_count = 0;
	ctx->hd_buf_filled = 0;
	return 0;
	}

	/*
	* DTS type IV (DTS-HD) can be transmitted with various frame repetition
	* periods; longer repetition periods allow for longer packets and therefore
	* higher bitrate. Longer repetition periods mean that the constant bitrate of
	* the outputted IEC 61937 stream is higher.
	* The repetition period is measured in IEC 60958 frames (4 bytes).
	*/
	static int spdif_dts4_subtype(int period)
	{
	switch (period) {
	case 512: return 0x0;
	case 1024: return 0x1;
	case 2048: return 0x2;
	case 4096: return 0x3;
	case 8192: return 0x4;
	case 16384: return 0x5;
	}
	return -1;
	}

	static int spdif_header_dts4(AVFormatContext s, AVPacket pkt, int core_size,
	int sample_rate, int blocks)
	{
	IEC61937Context *ctx = s->priv_data;
	static const char dtshd_start_code[10] = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfe, 0xfe };
	int pkt_size = pkt->size;
	int period;
	int subtype;

	if (!core_size) {
	av_log(s, AV_LOG_ERROR, "HD mode not supported for this format\n");
	return AVERROR(EINVAL);
	}

	if (!sample_rate) {
	av_log(s, AV_LOG_ERROR, "Unknown DTS sample rate for HD\n");
	return AVERROR_INVALIDDATA;
	}

	period = ctx->dtshd_rate * (blocks << 5) / sample_rate;
	subtype = spdif_dts4_subtype(period);

	if (subtype < 0) {
	av_log(s, AV_LOG_ERROR, "Specified HD rate of %d Hz would require an "
	"impossible repetition period of %d for the current DTS stream"
	" (blocks = %d, sample rate = %d)\n", ctx->dtshd_rate, period,
	blocks << 5, sample_rate);
	return AVERROR(EINVAL);
	}

	/* set pkt_offset and DTS IV subtype according to the requested output
	* rate */
	ctx->pkt_offset = period * 4;
	ctx->data_type = IEC61937_DTSHD \| subtype << 8;

	/* If the bitrate is too high for transmitting at the selected
	* repetition period setting, strip DTS-HD until a good amount
	* of consecutive non-overflowing HD frames have been observed.
	* This generally only happens if the caller is cramming a Master
	* Audio stream into 192kHz IEC 60958 (which may or may not fit). */
	if (sizeof(dtshd_start_code) + 2 + pkt_size
	> ctx->pkt_offset - BURST_HEADER_SIZE && core_size) {
	if (!ctx->dtshd_skip)
	av_log(s, AV_LOG_WARNING, "DTS-HD bitrate too high, "
	"temporarily sending core only\n");
	if (ctx->dtshd_fallback > 0)
	ctx->dtshd_skip = sample_rate * ctx->dtshd_fallback / (blocks << 5);
	else
	/* skip permanently (dtshd_fallback == -1) or just once
	* (dtshd_fallback == 0) */
	ctx->dtshd_skip = 1;
	}
	if (ctx->dtshd_skip && core_size) {
	pkt_size = core_size;
	if (ctx->dtshd_fallback >= 0)
	--ctx->dtshd_skip;
	}

	ctx->out_bytes = sizeof(dtshd_start_code) + 2 + pkt_size;

	/* Align so that (length_code & 0xf) == 0x8. This is reportedly needed
	* with some receivers, but the exact requirement is unconfirmed. */
	ctx->length_code = FFALIGN(ctx->out_bytes + 0x8, 0x10) - 0x8;

	av_fast_malloc(&ctx->hd_buf, &ctx->hd_buf_size, ctx->out_bytes);
	if (!ctx->hd_buf)
	return AVERROR(ENOMEM);

	ctx->out_buf = ctx->hd_buf;

	memcpy(ctx->hd_buf, dtshd_start_code, sizeof(dtshd_start_code));
	AV_WB16(ctx->hd_buf + sizeof(dtshd_start_code), pkt_size);
	memcpy(ctx->hd_buf + sizeof(dtshd_start_code) + 2, pkt->data, pkt_size);

	return 0;
	}

	static int spdif_header_dts(AVFormatContext s, AVPacket pkt)
	{
	IEC61937Context *ctx = s->priv_data;
	uint32_t syncword_dts = AV_RB32(pkt->data);
	int blocks;
	int sample_rate = 0;
	int core_size = 0;

	if (pkt->size < 9)
	return AVERROR_INVALIDDATA;

	switch (syncword_dts) {
	case DCA_SYNCWORD_CORE_BE:
	blocks = (AV_RB16(pkt->data + 4) >> 2) & 0x7f;
	core_size = ((AV_RB24(pkt->data + 5) >> 4) & 0x3fff) + 1;
	sample_rate = avpriv_dca_sample_rates[(pkt->data[8] >> 2) & 0x0f];
	break;
	case DCA_SYNCWORD_CORE_LE:
	blocks = (AV_RL16(pkt->data + 4) >> 2) & 0x7f;
	ctx->extra_bswap = 1;
	break;
	case DCA_SYNCWORD_CORE_14B_BE:
	blocks =
	(((pkt->data[5] & 0x07) << 4) \| ((pkt->data[6] & 0x3f) >> 2));
	break;
	case DCA_SYNCWORD_CORE_14B_LE:
	blocks =
	(((pkt->data[4] & 0x07) << 4) \| ((pkt->data[7] & 0x3f) >> 2));
	ctx->extra_bswap = 1;
	break;
	case DCA_SYNCWORD_SUBSTREAM:
	/* We only handle HD frames that are paired with core. However,
	sometimes DTS-HD streams with core have a stray HD frame without
	core in the beginning of the stream. */
	av_log(s, AV_LOG_ERROR, "stray DTS-HD frame\n");
	return AVERROR_INVALIDDATA;
	default:
	av_log(s, AV_LOG_ERROR, "bad DTS syncword 0x%"PRIx32"\n", syncword_dts);
	return AVERROR_INVALIDDATA;
	}
	blocks++;

	if (ctx->dtshd_rate)
	/* DTS type IV output requested */
	return spdif_header_dts4(s, pkt, core_size, sample_rate, blocks);

	switch (blocks) {
	case 512 >> 5: ctx->data_type = IEC61937_DTS1; break;
	case 1024 >> 5: ctx->data_type = IEC61937_DTS2; break;
	case 2048 >> 5: ctx->data_type = IEC61937_DTS3; break;
	default:
	av_log(s, AV_LOG_ERROR, "%i samples in DTS frame not supported\n",
	blocks << 5);
	return AVERROR(ENOSYS);
	}

	/* discard extraneous data by default */
	if (core_size && core_size < pkt->size) {
	ctx->out_bytes = core_size;
	ctx->length_code = core_size << 3;
	}

	ctx->pkt_offset = blocks << 7;

	if (ctx->out_bytes == ctx->pkt_offset) {
	/* The DTS stream fits exactly into the output stream, so skip the
	* preamble as it would not fit in there. This is the case for dts
	* discs and dts-in-wav. */
	ctx->use_preamble = 0;
	} else if (ctx->out_bytes > ctx->pkt_offset - BURST_HEADER_SIZE) {
	avpriv_request_sample(s, "Unrecognized large DTS frame");
	/* This will fail with a "bitrate too high" in the caller */
	}

	return 0;
	}

	static const enum IEC61937DataType mpeg_data_type[2][3] = {
	// LAYER1 LAYER2 LAYER3
	{ IEC61937_MPEG2_LAYER1_LSF, IEC61937_MPEG2_LAYER2_LSF, IEC61937_MPEG2_LAYER3_LSF },//MPEG2 LSF
	{ IEC61937_MPEG1_LAYER1, IEC61937_MPEG1_LAYER23, IEC61937_MPEG1_LAYER23 }, //MPEG1
	};

	static int spdif_header_mpeg(AVFormatContext s, AVPacket pkt)
	{
	IEC61937Context *ctx = s->priv_data;
	int version = (pkt->data[1] >> 3) & 3;
	int layer = 3 - ((pkt->data[1] >> 1) & 3);
	int extension = pkt->data[2] & 1;

	if (layer == 3 \|\| version == 1) {
	av_log(s, AV_LOG_ERROR, "Wrong MPEG file format\n");
	return AVERROR_INVALIDDATA;
	}
	av_log(s, AV_LOG_DEBUG, "version: %i layer: %i extension: %i\n", version, layer, extension);
	if (version == 2 && extension) {
	ctx->data_type = IEC61937_MPEG2_EXT;
	ctx->pkt_offset = 4608;
	} else {
	ctx->data_type = mpeg_data_type [version & 1][layer];
	ctx->pkt_offset = spdif_mpeg_pkt_offset[version & 1][layer];
	}
	// TODO Data type dependent info (normal/karaoke, dynamic range control)
	return 0;
	}

	static int spdif_header_aac(AVFormatContext s, AVPacket pkt)
	{
	IEC61937Context *ctx = s->priv_data;
	AACADTSHeaderInfo hdr;
	GetBitContext gbc;
	int ret;

	init_get_bits(&gbc, pkt->data, AAC_ADTS_HEADER_SIZE * 8);
	ret = avpriv_aac_parse_header(&gbc, &hdr);
	if (ret < 0) {
	av_log(s, AV_LOG_ERROR, "Wrong AAC file format\n");
	return AVERROR_INVALIDDATA;
	}

	ctx->pkt_offset = hdr.samples << 2;
	switch (hdr.num_aac_frames) {
	case 1:
	ctx->data_type = IEC61937_MPEG2_AAC;
	break;
	case 2:
	ctx->data_type = IEC61937_MPEG2_AAC_LSF_2048;
	break;
	case 4:
	ctx->data_type = IEC61937_MPEG2_AAC_LSF_4096;
	break;
	default:
	av_log(s, AV_LOG_ERROR,
	"%"PRIu32" samples in AAC frame not supported\n", hdr.samples);
	return AVERROR(EINVAL);
	}
	//TODO Data type dependent info (LC profile/SBR)
	return 0;
	}


	/*
	* It seems Dolby TrueHD frames have to be encapsulated in MAT frames before
	* they can be encapsulated in IEC 61937.
	* Here we encapsulate 24 TrueHD frames in a single MAT frame, padding them
	* to achieve constant rate.
	* The actual format of a MAT frame is unknown, but the below seems to work.
	* However, it seems it is not actually necessary for the 24 TrueHD frames to
	* be in an exact alignment with the MAT frame.
	*/
	#define MAT_FRAME_SIZE 61424
	#define TRUEHD_FRAME_OFFSET 2560
	#define MAT_MIDDLE_CODE_OFFSET -4

	static int spdif_header_truehd(AVFormatContext s, AVPacket pkt)
	{
	IEC61937Context *ctx = s->priv_data;
	int mat_code_length = 0;
	static const char mat_end_code[16] = { 0xC3, 0xC2, 0xC0, 0xC4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x97, 0x11 };

	if (!ctx->hd_buf_count) {
	static const char mat_start_code[20] = { 0x07, 0x9E, 0x00, 0x03, 0x84, 0x01, 0x01, 0x01, 0x80, 0x00, 0x56, 0xA5, 0x3B, 0xF4, 0x81, 0x83, 0x49, 0x80, 0x77, 0xE0 };
	mat_code_length = sizeof(mat_start_code) + BURST_HEADER_SIZE;
	memcpy(ctx->hd_buf, mat_start_code, sizeof(mat_start_code));

	} else if (ctx->hd_buf_count == 12) {
	static const char mat_middle_code[12] = { 0xC3, 0xC1, 0x42, 0x49, 0x3B, 0xFA, 0x82, 0x83, 0x49, 0x80, 0x77, 0xE0 };
	mat_code_length = sizeof(mat_middle_code) + MAT_MIDDLE_CODE_OFFSET;
	memcpy(&ctx->hd_buf[12 * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + MAT_MIDDLE_CODE_OFFSET],
	mat_middle_code, sizeof(mat_middle_code));
	}

	if (pkt->size > TRUEHD_FRAME_OFFSET - mat_code_length) {
	/* if such frames exist, we'd need some more complex logic to
	* distribute the TrueHD frames in the MAT frame */
	avpriv_request_sample(s, "Too large TrueHD frame of %d bytes",
	pkt->size);
	return AVERROR_PATCHWELCOME;
	}

	memcpy(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length],
	pkt->data, pkt->size);
	memset(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length + pkt->size],
	0, TRUEHD_FRAME_OFFSET - pkt->size - mat_code_length);

	if (++ctx->hd_buf_count < 24){
	ctx->pkt_offset = 0;
	return 0;
	}
	memcpy(&ctx->hd_buf[MAT_FRAME_SIZE - sizeof(mat_end_code)], mat_end_code, sizeof(mat_end_code));
	ctx->hd_buf_count = 0;

	ctx->data_type = IEC61937_TRUEHD;
	ctx->pkt_offset = 61440;
	ctx->out_buf = ctx->hd_buf;
	ctx->out_bytes = MAT_FRAME_SIZE;
	ctx->length_code = MAT_FRAME_SIZE;
	return 0;
	}

	static int spdif_write_header(AVFormatContext *s)
	{
	IEC61937Context *ctx = s->priv_data;

	switch (s->streams[0]->codec->codec_id) {
	case AV_CODEC_ID_AC3:
	ctx->header_info = spdif_header_ac3;
	break;
	case AV_CODEC_ID_EAC3:
	ctx->header_info = spdif_header_eac3;
	break;
	case AV_CODEC_ID_MP1:
	case AV_CODEC_ID_MP2:
	case AV_CODEC_ID_MP3:
	ctx->header_info = spdif_header_mpeg;
	break;
	case AV_CODEC_ID_DTS:
	ctx->header_info = spdif_header_dts;
	break;
	case AV_CODEC_ID_AAC:
	ctx->header_info = spdif_header_aac;
	break;
	case AV_CODEC_ID_TRUEHD:
	case AV_CODEC_ID_MLP:
	ctx->header_info = spdif_header_truehd;
	ctx->hd_buf = av_malloc(MAT_FRAME_SIZE);
	if (!ctx->hd_buf)
	return AVERROR(ENOMEM);
	break;
	default:
	av_log(s, AV_LOG_ERROR, "codec not supported\n");
	return AVERROR_PATCHWELCOME;
	}
	return 0;
	}

	static int spdif_write_trailer(AVFormatContext *s)
	{
	IEC61937Context *ctx = s->priv_data;
	av_freep(&ctx->buffer);
	av_freep(&ctx->hd_buf);
	return 0;
	}

	static av_always_inline void spdif_put_16(IEC61937Context *ctx,
	AVIOContext *pb, unsigned int val)
	{
	if (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)
	avio_wb16(pb, val);
	else
	avio_wl16(pb, val);
	}

	static int spdif_write_packet(struct AVFormatContext s, AVPacket pkt)
	{
	IEC61937Context *ctx = s->priv_data;
	int ret, padding;

	ctx->out_buf = pkt->data;
	ctx->out_bytes = pkt->size;
	ctx->length_code = FFALIGN(pkt->size, 2) << 3;
	ctx->use_preamble = 1;
	ctx->extra_bswap = 0;

	ret = ctx->header_info(s, pkt);
	if (ret < 0)
	return ret;
	if (!ctx->pkt_offset)
	return 0;

	padding = (ctx->pkt_offset - ctx->use_preamble * BURST_HEADER_SIZE - ctx->out_bytes) & ~1;
	if (padding < 0) {
	av_log(s, AV_LOG_ERROR, "bitrate is too high\n");
	return AVERROR(EINVAL);
	}

	if (ctx->use_preamble) {
	spdif_put_16(ctx, s->pb, SYNCWORD1); //Pa
	spdif_put_16(ctx, s->pb, SYNCWORD2); //Pb
	spdif_put_16(ctx, s->pb, ctx->data_type); //Pc
	spdif_put_16(ctx, s->pb, ctx->length_code);//Pd
	}

	if (ctx->extra_bswap ^ (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)) {
	avio_write(s->pb, ctx->out_buf, ctx->out_bytes & ~1);
	} else {
	av_fast_malloc(&ctx->buffer, &ctx->buffer_size, ctx->out_bytes + AV_INPUT_BUFFER_PADDING_SIZE);
	if (!ctx->buffer)
	return AVERROR(ENOMEM);
	ff_spdif_bswap_buf16((uint16_t )ctx->buffer, (uint16_t )ctx->out_buf, ctx->out_bytes >> 1);
	avio_write(s->pb, ctx->buffer, ctx->out_bytes & ~1);
	}

	/* a final lone byte has to be MSB aligned */
	if (ctx->out_bytes & 1)
	spdif_put_16(ctx, s->pb, ctx->out_buf[ctx->out_bytes - 1] << 8);

	ffio_fill(s->pb, 0, padding);

	av_log(s, AV_LOG_DEBUG, "type=%x len=%i pkt_offset=%i\n",
	ctx->data_type, ctx->out_bytes, ctx->pkt_offset);

	return 0;
	}

	AVOutputFormat ff_spdif_muxer = {
	.name = "spdif",
	.long_name = NULL_IF_CONFIG_SMALL("IEC 61937 (used on S/PDIF - IEC958)"),
	.extensions = "spdif",
	.priv_data_size = sizeof(IEC61937Context),
	.audio_codec = AV_CODEC_ID_AC3,
	.video_codec = AV_CODEC_ID_NONE,
	.write_header = spdif_write_header,
	.write_packet = spdif_write_packet,
	.write_trailer = spdif_write_trailer,
	.flags = AVFMT_NOTIMESTAMPS,
	.priv_class = &spdif_class,
	};