| /* |
| * ALAC (Apple Lossless Audio Codec) decoder |
| * Copyright (c) 2005 David Hammerton |
| * |
| * 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 |
| * ALAC (Apple Lossless Audio Codec) decoder |
| * @author 2005 David Hammerton |
| * @see http://crazney.net/programs/itunes/alac.html |
| * |
| * Note: This decoder expects a 36-byte QuickTime atom to be |
| * passed through the extradata[_size] fields. This atom is tacked onto |
| * the end of an 'alac' stsd atom and has the following format: |
| * |
| * 32bit atom size |
| * 32bit tag ("alac") |
| * 32bit tag version (0) |
| * 32bit samples per frame (used when not set explicitly in the frames) |
| * 8bit compatible version (0) |
| * 8bit sample size |
| * 8bit history mult (40) |
| * 8bit initial history (10) |
| * 8bit rice param limit (14) |
| * 8bit channels |
| * 16bit maxRun (255) |
| * 32bit max coded frame size (0 means unknown) |
| * 32bit average bitrate (0 means unknown) |
| * 32bit samplerate |
| */ |
| |
| #include <inttypes.h> |
| |
| #include "libavutil/channel_layout.h" |
| #include "libavutil/opt.h" |
| #include "avcodec.h" |
| #include "get_bits.h" |
| #include "bytestream.h" |
| #include "internal.h" |
| #include "thread.h" |
| #include "unary.h" |
| #include "mathops.h" |
| #include "alac_data.h" |
| #include "alacdsp.h" |
| |
| #define ALAC_EXTRADATA_SIZE 36 |
| |
| typedef struct ALACContext { |
| AVClass *class; |
| AVCodecContext *avctx; |
| GetBitContext gb; |
| int channels; |
| |
| int32_t *predict_error_buffer[2]; |
| int32_t *output_samples_buffer[2]; |
| int32_t *extra_bits_buffer[2]; |
| |
| uint32_t max_samples_per_frame; |
| uint8_t sample_size; |
| uint8_t rice_history_mult; |
| uint8_t rice_initial_history; |
| uint8_t rice_limit; |
| |
| int extra_bits; /**< number of extra bits beyond 16-bit */ |
| int nb_samples; /**< number of samples in the current frame */ |
| |
| int direct_output; |
| int extra_bit_bug; |
| |
| ALACDSPContext dsp; |
| } ALACContext; |
| |
| static inline unsigned int decode_scalar(GetBitContext *gb, int k, int bps) |
| { |
| unsigned int x = get_unary_0_9(gb); |
| |
| if (x > 8) { /* RICE THRESHOLD */ |
| /* use alternative encoding */ |
| x = get_bits_long(gb, bps); |
| } else if (k != 1) { |
| int extrabits = show_bits(gb, k); |
| |
| /* multiply x by 2^k - 1, as part of their strange algorithm */ |
| x = (x << k) - x; |
| |
| if (extrabits > 1) { |
| x += extrabits - 1; |
| skip_bits(gb, k); |
| } else |
| skip_bits(gb, k - 1); |
| } |
| return x; |
| } |
| |
| static int rice_decompress(ALACContext *alac, int32_t *output_buffer, |
| int nb_samples, int bps, int rice_history_mult) |
| { |
| int i; |
| unsigned int history = alac->rice_initial_history; |
| int sign_modifier = 0; |
| |
| for (i = 0; i < nb_samples; i++) { |
| int k; |
| unsigned int x; |
| |
| if(get_bits_left(&alac->gb) <= 0) |
| return -1; |
| |
| /* calculate rice param and decode next value */ |
| k = av_log2((history >> 9) + 3); |
| k = FFMIN(k, alac->rice_limit); |
| x = decode_scalar(&alac->gb, k, bps); |
| x += sign_modifier; |
| sign_modifier = 0; |
| output_buffer[i] = (x >> 1) ^ -(x & 1); |
| |
| /* update the history */ |
| if (x > 0xffff) |
| history = 0xffff; |
| else |
| history += x * rice_history_mult - |
| ((history * rice_history_mult) >> 9); |
| |
| /* special case: there may be compressed blocks of 0 */ |
| if ((history < 128) && (i + 1 < nb_samples)) { |
| int block_size; |
| |
| /* calculate rice param and decode block size */ |
| k = 7 - av_log2(history) + ((history + 16) >> 6); |
| k = FFMIN(k, alac->rice_limit); |
| block_size = decode_scalar(&alac->gb, k, 16); |
| |
| if (block_size > 0) { |
| if (block_size >= nb_samples - i) { |
| av_log(alac->avctx, AV_LOG_ERROR, |
| "invalid zero block size of %d %d %d\n", block_size, |
| nb_samples, i); |
| block_size = nb_samples - i - 1; |
| } |
| memset(&output_buffer[i + 1], 0, |
| block_size * sizeof(*output_buffer)); |
| i += block_size; |
| } |
| if (block_size <= 0xffff) |
| sign_modifier = 1; |
| history = 0; |
| } |
| } |
| return 0; |
| } |
| |
| static inline int sign_only(int v) |
| { |
| return v ? FFSIGN(v) : 0; |
| } |
| |
| static void lpc_prediction(int32_t *error_buffer, int32_t *buffer_out, |
| int nb_samples, int bps, int16_t *lpc_coefs, |
| int lpc_order, int lpc_quant) |
| { |
| int i; |
| int32_t *pred = buffer_out; |
| |
| /* first sample always copies */ |
| *buffer_out = *error_buffer; |
| |
| if (nb_samples <= 1) |
| return; |
| |
| if (!lpc_order) { |
| memcpy(&buffer_out[1], &error_buffer[1], |
| (nb_samples - 1) * sizeof(*buffer_out)); |
| return; |
| } |
| |
| if (lpc_order == 31) { |
| /* simple 1st-order prediction */ |
| for (i = 1; i < nb_samples; i++) { |
| buffer_out[i] = sign_extend(buffer_out[i - 1] + error_buffer[i], |
| bps); |
| } |
| return; |
| } |
| |
| /* read warm-up samples */ |
| for (i = 1; i <= lpc_order && i < nb_samples; i++) |
| buffer_out[i] = sign_extend(buffer_out[i - 1] + error_buffer[i], bps); |
| |
| /* NOTE: 4 and 8 are very common cases that could be optimized. */ |
| |
| for (; i < nb_samples; i++) { |
| int j; |
| int val = 0; |
| int error_val = error_buffer[i]; |
| int error_sign; |
| int d = *pred++; |
| |
| /* LPC prediction */ |
| for (j = 0; j < lpc_order; j++) |
| val += (pred[j] - d) * lpc_coefs[j]; |
| val = (val + (1 << (lpc_quant - 1))) >> lpc_quant; |
| val += d + error_val; |
| buffer_out[i] = sign_extend(val, bps); |
| |
| /* adapt LPC coefficients */ |
| error_sign = sign_only(error_val); |
| if (error_sign) { |
| for (j = 0; j < lpc_order && error_val * error_sign > 0; j++) { |
| int sign; |
| val = d - pred[j]; |
| sign = sign_only(val) * error_sign; |
| lpc_coefs[j] -= sign; |
| val *= sign; |
| error_val -= (val >> lpc_quant) * (j + 1); |
| } |
| } |
| } |
| } |
| |
| static int decode_element(AVCodecContext *avctx, AVFrame *frame, int ch_index, |
| int channels) |
| { |
| ALACContext *alac = avctx->priv_data; |
| int has_size, bps, is_compressed, decorr_shift, decorr_left_weight, ret; |
| uint32_t output_samples; |
| int i, ch; |
| |
| skip_bits(&alac->gb, 4); /* element instance tag */ |
| skip_bits(&alac->gb, 12); /* unused header bits */ |
| |
| /* the number of output samples is stored in the frame */ |
| has_size = get_bits1(&alac->gb); |
| |
| alac->extra_bits = get_bits(&alac->gb, 2) << 3; |
| bps = alac->sample_size - alac->extra_bits + channels - 1; |
| if (bps > 32U) { |
| av_log(avctx, AV_LOG_ERROR, "bps is unsupported: %d\n", bps); |
| return AVERROR_PATCHWELCOME; |
| } |
| |
| /* whether the frame is compressed */ |
| is_compressed = !get_bits1(&alac->gb); |
| |
| if (has_size) |
| output_samples = get_bits_long(&alac->gb, 32); |
| else |
| output_samples = alac->max_samples_per_frame; |
| if (!output_samples || output_samples > alac->max_samples_per_frame) { |
| av_log(avctx, AV_LOG_ERROR, "invalid samples per frame: %"PRIu32"\n", |
| output_samples); |
| return AVERROR_INVALIDDATA; |
| } |
| if (!alac->nb_samples) { |
| ThreadFrame tframe = { .f = frame }; |
| /* get output buffer */ |
| frame->nb_samples = output_samples; |
| if ((ret = ff_thread_get_buffer(avctx, &tframe, 0)) < 0) |
| return ret; |
| } else if (output_samples != alac->nb_samples) { |
| av_log(avctx, AV_LOG_ERROR, "sample count mismatch: %"PRIu32" != %d\n", |
| output_samples, alac->nb_samples); |
| return AVERROR_INVALIDDATA; |
| } |
| alac->nb_samples = output_samples; |
| if (alac->direct_output) { |
| for (ch = 0; ch < channels; ch++) |
| alac->output_samples_buffer[ch] = (int32_t *)frame->extended_data[ch_index + ch]; |
| } |
| |
| if (is_compressed) { |
| int16_t lpc_coefs[2][32]; |
| int lpc_order[2]; |
| int prediction_type[2]; |
| int lpc_quant[2]; |
| int rice_history_mult[2]; |
| |
| if (!alac->rice_limit) { |
| avpriv_request_sample(alac->avctx, |
| "Compression with rice limit 0"); |
| return AVERROR(ENOSYS); |
| } |
| |
| decorr_shift = get_bits(&alac->gb, 8); |
| decorr_left_weight = get_bits(&alac->gb, 8); |
| |
| for (ch = 0; ch < channels; ch++) { |
| prediction_type[ch] = get_bits(&alac->gb, 4); |
| lpc_quant[ch] = get_bits(&alac->gb, 4); |
| rice_history_mult[ch] = get_bits(&alac->gb, 3); |
| lpc_order[ch] = get_bits(&alac->gb, 5); |
| |
| if (lpc_order[ch] >= alac->max_samples_per_frame) |
| return AVERROR_INVALIDDATA; |
| |
| /* read the predictor table */ |
| for (i = lpc_order[ch] - 1; i >= 0; i--) |
| lpc_coefs[ch][i] = get_sbits(&alac->gb, 16); |
| } |
| |
| if (alac->extra_bits) { |
| for (i = 0; i < alac->nb_samples; i++) { |
| if(get_bits_left(&alac->gb) <= 0) |
| return -1; |
| for (ch = 0; ch < channels; ch++) |
| alac->extra_bits_buffer[ch][i] = get_bits(&alac->gb, alac->extra_bits); |
| } |
| } |
| for (ch = 0; ch < channels; ch++) { |
| int ret=rice_decompress(alac, alac->predict_error_buffer[ch], |
| alac->nb_samples, bps, |
| rice_history_mult[ch] * alac->rice_history_mult / 4); |
| if(ret<0) |
| return ret; |
| |
| /* adaptive FIR filter */ |
| if (prediction_type[ch] == 15) { |
| /* Prediction type 15 runs the adaptive FIR twice. |
| * The first pass uses the special-case coef_num = 31, while |
| * the second pass uses the coefs from the bitstream. |
| * |
| * However, this prediction type is not currently used by the |
| * reference encoder. |
| */ |
| lpc_prediction(alac->predict_error_buffer[ch], |
| alac->predict_error_buffer[ch], |
| alac->nb_samples, bps, NULL, 31, 0); |
| } else if (prediction_type[ch] > 0) { |
| av_log(avctx, AV_LOG_WARNING, "unknown prediction type: %i\n", |
| prediction_type[ch]); |
| } |
| lpc_prediction(alac->predict_error_buffer[ch], |
| alac->output_samples_buffer[ch], alac->nb_samples, |
| bps, lpc_coefs[ch], lpc_order[ch], lpc_quant[ch]); |
| } |
| } else { |
| /* not compressed, easy case */ |
| for (i = 0; i < alac->nb_samples; i++) { |
| if(get_bits_left(&alac->gb) <= 0) |
| return -1; |
| for (ch = 0; ch < channels; ch++) { |
| alac->output_samples_buffer[ch][i] = |
| get_sbits_long(&alac->gb, alac->sample_size); |
| } |
| } |
| alac->extra_bits = 0; |
| decorr_shift = 0; |
| decorr_left_weight = 0; |
| } |
| |
| if (channels == 2) { |
| if (alac->extra_bits && alac->extra_bit_bug) { |
| alac->dsp.append_extra_bits[1](alac->output_samples_buffer, alac->extra_bits_buffer, |
| alac->extra_bits, channels, alac->nb_samples); |
| } |
| |
| if (decorr_left_weight) { |
| alac->dsp.decorrelate_stereo(alac->output_samples_buffer, alac->nb_samples, |
| decorr_shift, decorr_left_weight); |
| } |
| |
| if (alac->extra_bits && !alac->extra_bit_bug) { |
| alac->dsp.append_extra_bits[1](alac->output_samples_buffer, alac->extra_bits_buffer, |
| alac->extra_bits, channels, alac->nb_samples); |
| } |
| } else if (alac->extra_bits) { |
| alac->dsp.append_extra_bits[0](alac->output_samples_buffer, alac->extra_bits_buffer, |
| alac->extra_bits, channels, alac->nb_samples); |
| } |
| |
| switch(alac->sample_size) { |
| case 16: { |
| for (ch = 0; ch < channels; ch++) { |
| int16_t *outbuffer = (int16_t *)frame->extended_data[ch_index + ch]; |
| for (i = 0; i < alac->nb_samples; i++) |
| *outbuffer++ = alac->output_samples_buffer[ch][i]; |
| }} |
| break; |
| case 24: { |
| for (ch = 0; ch < channels; ch++) { |
| for (i = 0; i < alac->nb_samples; i++) |
| alac->output_samples_buffer[ch][i] <<= 8; |
| }} |
| break; |
| } |
| |
| return 0; |
| } |
| |
| static int alac_decode_frame(AVCodecContext *avctx, void *data, |
| int *got_frame_ptr, AVPacket *avpkt) |
| { |
| ALACContext *alac = avctx->priv_data; |
| AVFrame *frame = data; |
| enum AlacRawDataBlockType element; |
| int channels; |
| int ch, ret, got_end; |
| |
| if ((ret = init_get_bits8(&alac->gb, avpkt->data, avpkt->size)) < 0) |
| return ret; |
| |
| got_end = 0; |
| alac->nb_samples = 0; |
| ch = 0; |
| while (get_bits_left(&alac->gb) >= 3) { |
| element = get_bits(&alac->gb, 3); |
| if (element == TYPE_END) { |
| got_end = 1; |
| break; |
| } |
| if (element > TYPE_CPE && element != TYPE_LFE) { |
| av_log(avctx, AV_LOG_ERROR, "syntax element unsupported: %d\n", element); |
| return AVERROR_PATCHWELCOME; |
| } |
| |
| channels = (element == TYPE_CPE) ? 2 : 1; |
| if (ch + channels > alac->channels || |
| ff_alac_channel_layout_offsets[alac->channels - 1][ch] + channels > alac->channels) { |
| av_log(avctx, AV_LOG_ERROR, "invalid element channel count\n"); |
| return AVERROR_INVALIDDATA; |
| } |
| |
| ret = decode_element(avctx, frame, |
| ff_alac_channel_layout_offsets[alac->channels - 1][ch], |
| channels); |
| if (ret < 0 && get_bits_left(&alac->gb)) |
| return ret; |
| |
| ch += channels; |
| } |
| if (!got_end) { |
| av_log(avctx, AV_LOG_ERROR, "no end tag found. incomplete packet.\n"); |
| return AVERROR_INVALIDDATA; |
| } |
| |
| if (avpkt->size * 8 - get_bits_count(&alac->gb) > 8) { |
| av_log(avctx, AV_LOG_ERROR, "Error : %d bits left\n", |
| avpkt->size * 8 - get_bits_count(&alac->gb)); |
| } |
| |
| if (alac->channels == ch) |
| *got_frame_ptr = 1; |
| else |
| av_log(avctx, AV_LOG_WARNING, "Failed to decode all channels\n"); |
| |
| return avpkt->size; |
| } |
| |
| static av_cold int alac_decode_close(AVCodecContext *avctx) |
| { |
| ALACContext *alac = avctx->priv_data; |
| |
| int ch; |
| for (ch = 0; ch < FFMIN(alac->channels, 2); ch++) { |
| av_freep(&alac->predict_error_buffer[ch]); |
| if (!alac->direct_output) |
| av_freep(&alac->output_samples_buffer[ch]); |
| av_freep(&alac->extra_bits_buffer[ch]); |
| } |
| |
| return 0; |
| } |
| |
| static int allocate_buffers(ALACContext *alac) |
| { |
| int ch; |
| int buf_size = alac->max_samples_per_frame * sizeof(int32_t); |
| |
| for (ch = 0; ch < 2; ch++) { |
| alac->predict_error_buffer[ch] = NULL; |
| alac->output_samples_buffer[ch] = NULL; |
| alac->extra_bits_buffer[ch] = NULL; |
| } |
| |
| for (ch = 0; ch < FFMIN(alac->channels, 2); ch++) { |
| FF_ALLOC_OR_GOTO(alac->avctx, alac->predict_error_buffer[ch], |
| buf_size, buf_alloc_fail); |
| |
| alac->direct_output = alac->sample_size > 16; |
| if (!alac->direct_output) { |
| FF_ALLOC_OR_GOTO(alac->avctx, alac->output_samples_buffer[ch], |
| buf_size + AV_INPUT_BUFFER_PADDING_SIZE, buf_alloc_fail); |
| } |
| |
| FF_ALLOC_OR_GOTO(alac->avctx, alac->extra_bits_buffer[ch], |
| buf_size + AV_INPUT_BUFFER_PADDING_SIZE, buf_alloc_fail); |
| } |
| return 0; |
| buf_alloc_fail: |
| alac_decode_close(alac->avctx); |
| return AVERROR(ENOMEM); |
| } |
| |
| static int alac_set_info(ALACContext *alac) |
| { |
| GetByteContext gb; |
| |
| bytestream2_init(&gb, alac->avctx->extradata, |
| alac->avctx->extradata_size); |
| |
| bytestream2_skipu(&gb, 12); // size:4, alac:4, version:4 |
| |
| alac->max_samples_per_frame = bytestream2_get_be32u(&gb); |
| if (!alac->max_samples_per_frame || |
| alac->max_samples_per_frame > INT_MAX / sizeof(int32_t)) { |
| av_log(alac->avctx, AV_LOG_ERROR, |
| "max samples per frame invalid: %"PRIu32"\n", |
| alac->max_samples_per_frame); |
| return AVERROR_INVALIDDATA; |
| } |
| bytestream2_skipu(&gb, 1); // compatible version |
| alac->sample_size = bytestream2_get_byteu(&gb); |
| alac->rice_history_mult = bytestream2_get_byteu(&gb); |
| alac->rice_initial_history = bytestream2_get_byteu(&gb); |
| alac->rice_limit = bytestream2_get_byteu(&gb); |
| alac->channels = bytestream2_get_byteu(&gb); |
| bytestream2_get_be16u(&gb); // maxRun |
| bytestream2_get_be32u(&gb); // max coded frame size |
| bytestream2_get_be32u(&gb); // average bitrate |
| bytestream2_get_be32u(&gb); // samplerate |
| |
| return 0; |
| } |
| |
| static av_cold int alac_decode_init(AVCodecContext * avctx) |
| { |
| int ret; |
| ALACContext *alac = avctx->priv_data; |
| alac->avctx = avctx; |
| |
| /* initialize from the extradata */ |
| if (alac->avctx->extradata_size < ALAC_EXTRADATA_SIZE) { |
| av_log(avctx, AV_LOG_ERROR, "extradata is too small\n"); |
| return AVERROR_INVALIDDATA; |
| } |
| if (alac_set_info(alac)) { |
| av_log(avctx, AV_LOG_ERROR, "set_info failed\n"); |
| return -1; |
| } |
| |
| switch (alac->sample_size) { |
| case 16: avctx->sample_fmt = AV_SAMPLE_FMT_S16P; |
| break; |
| case 24: |
| case 32: avctx->sample_fmt = AV_SAMPLE_FMT_S32P; |
| break; |
| default: avpriv_request_sample(avctx, "Sample depth %d", alac->sample_size); |
| return AVERROR_PATCHWELCOME; |
| } |
| avctx->bits_per_raw_sample = alac->sample_size; |
| |
| if (alac->channels < 1) { |
| av_log(avctx, AV_LOG_WARNING, "Invalid channel count\n"); |
| alac->channels = avctx->channels; |
| } else { |
| if (alac->channels > ALAC_MAX_CHANNELS) |
| alac->channels = avctx->channels; |
| else |
| avctx->channels = alac->channels; |
| } |
| if (avctx->channels > ALAC_MAX_CHANNELS || avctx->channels <= 0 ) { |
| av_log(avctx, AV_LOG_ERROR, "Unsupported channel count: %d\n", |
| avctx->channels); |
| return AVERROR_PATCHWELCOME; |
| } |
| avctx->channel_layout = ff_alac_channel_layouts[alac->channels - 1]; |
| |
| if ((ret = allocate_buffers(alac)) < 0) { |
| av_log(avctx, AV_LOG_ERROR, "Error allocating buffers\n"); |
| return ret; |
| } |
| |
| ff_alacdsp_init(&alac->dsp); |
| |
| return 0; |
| } |
| |
| #if HAVE_THREADS |
| static int init_thread_copy(AVCodecContext *avctx) |
| { |
| ALACContext *alac = avctx->priv_data; |
| alac->avctx = avctx; |
| return allocate_buffers(alac); |
| } |
| #endif |
| |
| static const AVOption options[] = { |
| { "extra_bits_bug", "Force non-standard decoding process", |
| offsetof(ALACContext, extra_bit_bug), AV_OPT_TYPE_BOOL, { .i64 = 0 }, |
| 0, 1, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM }, |
| { NULL }, |
| }; |
| |
| static const AVClass alac_class = { |
| .class_name = "alac", |
| .item_name = av_default_item_name, |
| .option = options, |
| .version = LIBAVUTIL_VERSION_INT, |
| }; |
| |
| AVCodec ff_alac_decoder = { |
| .name = "alac", |
| .long_name = NULL_IF_CONFIG_SMALL("ALAC (Apple Lossless Audio Codec)"), |
| .type = AVMEDIA_TYPE_AUDIO, |
| .id = AV_CODEC_ID_ALAC, |
| .priv_data_size = sizeof(ALACContext), |
| .init = alac_decode_init, |
| .close = alac_decode_close, |
| .decode = alac_decode_frame, |
| .init_thread_copy = ONLY_IF_THREADS_ENABLED(init_thread_copy), |
| .capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS, |
| .priv_class = &alac_class |
| }; |
