libavformat/nuv.c - manifest_repos/ffmpeg - Git at Google

 /*
  * NuppelVideo demuxer.
  * Copyright (c) 2006 Reimar Doeffinger
  *
  * 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
  */

 #include "libavutil/channel_layout.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/intfloat.h"
 #include "avformat.h"
 #include "internal.h"
 #include "riff.h"

 static const AVCodecTag nuv_audio_tags[] = {
     { AV_CODEC_ID_PCM_S16LE, MKTAG('R', 'A', 'W', 'A') },
     { AV_CODEC_ID_MP3,       MKTAG('L', 'A', 'M', 'E') },
     { AV_CODEC_ID_NONE,      0 },
 };

 typedef struct NUVContext {
     int v_id;
     int a_id;
     int rtjpg_video;
 } NUVContext;

 typedef enum {
     NUV_VIDEO     = 'V',
     NUV_EXTRADATA = 'D',
     NUV_AUDIO     = 'A',
     NUV_SEEKP     = 'R',
     NUV_MYTHEXT   = 'X'
 } nuv_frametype;

 static int nuv_probe(const AVProbeData *p)
 {
     if (!memcmp(p->buf, "NuppelVideo", 12))
         return AVPROBE_SCORE_MAX;
     if (!memcmp(p->buf, "MythTVVideo", 12))
         return AVPROBE_SCORE_MAX;
     return 0;
 }

 /// little macro to sanitize packet size
 #define PKTSIZE(s) (s &  0xffffff)

 /**
  * @brief read until we found all data needed for decoding
  * @param vst video stream of which to change parameters
  * @param ast video stream of which to change parameters
  * @param myth set if this is a MythTVVideo format file
  * @return 0 or AVERROR code
  */
 static int get_codec_data(AVFormatContext *s, AVIOContext *pb, AVStream *vst,
                           AVStream *ast, int myth)
 {
     nuv_frametype frametype;

     if (!vst && !myth)
         return 1; // no codec data needed
     while (!avio_feof(pb)) {
         int size, subtype, ret;

         frametype = avio_r8(pb);
         switch (frametype) {
         case NUV_EXTRADATA:
             subtype = avio_r8(pb);
             avio_skip(pb, 6);
             size = PKTSIZE(avio_rl32(pb));
             if (vst && subtype == 'R') {
                 if ((ret = ff_get_extradata(NULL, vst->codecpar, pb, size)) < 0)
                     return ret;
                 size = 0;
                 if (!myth)
                     return 0;
             }
             break;
         case NUV_MYTHEXT:
             avio_skip(pb, 7);
             size = PKTSIZE(avio_rl32(pb));
             if (size != 128 * 4)
                 break;
             avio_rl32(pb); // version
             if (vst) {
                 vst->codecpar->codec_tag = avio_rl32(pb);
                 vst->codecpar->codec_id =
                     ff_codec_get_id(ff_codec_bmp_tags, vst->codecpar->codec_tag);
                 if (vst->codecpar->codec_tag == MKTAG('R', 'J', 'P', 'G'))
                     vst->codecpar->codec_id = AV_CODEC_ID_NUV;
             } else
                 avio_skip(pb, 4);

             if (ast) {
                 int id;

                 ast->codecpar->codec_tag             = avio_rl32(pb);
                 ast->codecpar->sample_rate           = avio_rl32(pb);
                 if (ast->codecpar->sample_rate <= 0) {
                     av_log(s, AV_LOG_ERROR, "Invalid sample rate %d\n", ast->codecpar->sample_rate);
                     return AVERROR_INVALIDDATA;
                 }
                 ast->codecpar->bits_per_coded_sample = avio_rl32(pb);
                 ast->codecpar->channels              = avio_rl32(pb);
                 ast->codecpar->channel_layout        = 0;

                 id = ff_wav_codec_get_id(ast->codecpar->codec_tag,
                                          ast->codecpar->bits_per_coded_sample);
                 if (id == AV_CODEC_ID_NONE) {
                     id = ff_codec_get_id(nuv_audio_tags, ast->codecpar->codec_tag);
                     if (id == AV_CODEC_ID_PCM_S16LE)
                         id = ff_get_pcm_codec_id(ast->codecpar->bits_per_coded_sample,
                                                  0, 0, ~1);
                 }
                 ast->codecpar->codec_id = id;

                 ast->need_parsing = AVSTREAM_PARSE_FULL;
             } else
                 avio_skip(pb, 4 * 4);

             size -= 6 * 4;
             avio_skip(pb, size);
             return 0;
         case NUV_SEEKP:
             size = 11;
             break;
         default:
             avio_skip(pb, 7);
             size = PKTSIZE(avio_rl32(pb));
             break;
         }
         avio_skip(pb, size);
     }

     return 0;
 }

 static int nuv_header(AVFormatContext *s)
 {
     NUVContext *ctx = s->priv_data;
     AVIOContext *pb = s->pb;
     char id_string[12];
     double aspect, fps;
     int is_mythtv, width, height, v_packs, a_packs, ret;
     AVStream *vst = NULL, *ast = NULL;

     avio_read(pb, id_string, 12);
     is_mythtv = !memcmp(id_string, "MythTVVideo", 12);
     avio_skip(pb, 5);       // version string
     avio_skip(pb, 3);       // padding
     width  = avio_rl32(pb);
     height = avio_rl32(pb);
     avio_rl32(pb);          // unused, "desiredwidth"
     avio_rl32(pb);          // unused, "desiredheight"
     avio_r8(pb);            // 'P' == progressive, 'I' == interlaced
     avio_skip(pb, 3);       // padding
     aspect = av_int2double(avio_rl64(pb));
     if (aspect > 0.9999 && aspect < 1.0001)
         aspect = 4.0 / 3.0;
     fps = av_int2double(avio_rl64(pb));
     if (fps < 0.0f) {
         if (s->error_recognition & AV_EF_EXPLODE) {
             av_log(s, AV_LOG_ERROR, "Invalid frame rate %f\n", fps);
             return AVERROR_INVALIDDATA;
         } else {
             av_log(s, AV_LOG_WARNING, "Invalid frame rate %f, setting to 0.\n", fps);
             fps = 0.0f;
         }
     }

     // number of packets per stream type, -1 means unknown, e.g. streaming
     v_packs = avio_rl32(pb);
     a_packs = avio_rl32(pb);
     avio_rl32(pb); // text

     avio_rl32(pb); // keyframe distance (?)

     if (v_packs) {
         vst = avformat_new_stream(s, NULL);
         if (!vst)
             return AVERROR(ENOMEM);
         ctx->v_id = vst->index;

         ret = av_image_check_size(width, height, 0, s);
         if (ret < 0)
             return ret;

         vst->codecpar->codec_type            = AVMEDIA_TYPE_VIDEO;
         vst->codecpar->codec_id              = AV_CODEC_ID_NUV;
         vst->codecpar->width                 = width;
         vst->codecpar->height                = height;
         vst->codecpar->bits_per_coded_sample = 10;
         vst->sample_aspect_ratio          = av_d2q(aspect * height / width,
                                                    10000);
 #if FF_API_R_FRAME_RATE
         vst->r_frame_rate =
 #endif
         vst->avg_frame_rate = av_d2q(fps, 60000);
         avpriv_set_pts_info(vst, 32, 1, 1000);
     } else
         ctx->v_id = -1;

     if (a_packs) {
         ast = avformat_new_stream(s, NULL);
         if (!ast)
             return AVERROR(ENOMEM);
         ctx->a_id = ast->index;

         ast->codecpar->codec_type            = AVMEDIA_TYPE_AUDIO;
         ast->codecpar->codec_id              = AV_CODEC_ID_PCM_S16LE;
         ast->codecpar->channels              = 2;
         ast->codecpar->channel_layout        = AV_CH_LAYOUT_STEREO;
         ast->codecpar->sample_rate           = 44100;
         ast->codecpar->bit_rate              = 2 * 2 * 44100 * 8;
         ast->codecpar->block_align           = 2 * 2;
         ast->codecpar->bits_per_coded_sample = 16;
         avpriv_set_pts_info(ast, 32, 1, 1000);
     } else
         ctx->a_id = -1;

     if ((ret = get_codec_data(s, pb, vst, ast, is_mythtv)) < 0)
         return ret;

     ctx->rtjpg_video = vst && vst->codecpar->codec_id == AV_CODEC_ID_NUV;

     return 0;
 }

 #define HDRSIZE 12

 static int nuv_packet(AVFormatContext *s, AVPacket *pkt)
 {
     NUVContext *ctx = s->priv_data;
     AVIOContext *pb = s->pb;
     uint8_t hdr[HDRSIZE];
     nuv_frametype frametype;
     int ret, size;

     while (!avio_feof(pb)) {
         int copyhdrsize = ctx->rtjpg_video ? HDRSIZE : 0;
         uint64_t pos    = avio_tell(pb);

         ret = avio_read(pb, hdr, HDRSIZE);
         if (ret < HDRSIZE)
             return ret < 0 ? ret : AVERROR(EIO);

         frametype = hdr[0];
         size      = PKTSIZE(AV_RL32(&hdr[8]));

         switch (frametype) {
         case NUV_EXTRADATA:
             if (!ctx->rtjpg_video) {
                 avio_skip(pb, size);
                 break;
             }
         case NUV_VIDEO:
             if (ctx->v_id < 0) {
                 av_log(s, AV_LOG_ERROR, "Video packet in file without video stream!\n");
                 avio_skip(pb, size);
                 break;
             }
             ret = av_new_packet(pkt, copyhdrsize + size);
             if (ret < 0)
                 return ret;

             pkt->pos          = pos;
             pkt->flags       |= hdr[2] == 0 ? AV_PKT_FLAG_KEY : 0;
             pkt->pts          = AV_RL32(&hdr[4]);
             pkt->stream_index = ctx->v_id;
             memcpy(pkt->data, hdr, copyhdrsize);
             ret = avio_read(pb, pkt->data + copyhdrsize, size);
             if (ret < 0) {
                 return ret;
             }
             if (ret < size)
                 av_shrink_packet(pkt, copyhdrsize + ret);
             return 0;
         case NUV_AUDIO:
             if (ctx->a_id < 0) {
                 av_log(s, AV_LOG_ERROR, "Audio packet in file without audio stream!\n");
                 avio_skip(pb, size);
                 break;
             }
             ret               = av_get_packet(pb, pkt, size);
             pkt->flags       |= AV_PKT_FLAG_KEY;
             pkt->pos          = pos;
             pkt->pts          = AV_RL32(&hdr[4]);
             pkt->stream_index = ctx->a_id;
             if (ret < 0)
                 return ret;
             return 0;
         case NUV_SEEKP:
             // contains no data, size value is invalid
             break;
         default:
             avio_skip(pb, size);
             break;
         }
     }

     return AVERROR(EIO);
 }

 /**
  * \brief looks for the string RTjjjjjjjjjj in the stream too resync reading
  * \return 1 if the syncword is found 0 otherwise.
  */
 static int nuv_resync(AVFormatContext *s, int64_t pos_limit) {
     AVIOContext *pb = s->pb;
     uint32_t tag = 0;
     while(!avio_feof(pb) && avio_tell(pb) < pos_limit) {
         tag = (tag << 8) | avio_r8(pb);
         if (tag                  == MKBETAG('R','T','j','j') &&
            (tag = avio_rb32(pb)) == MKBETAG('j','j','j','j') &&
            (tag = avio_rb32(pb)) == MKBETAG('j','j','j','j'))
             return 1;
     }
     return 0;
 }

 /**
  * \brief attempts to read a timestamp from stream at the given stream position
  * \return timestamp if successful and AV_NOPTS_VALUE if failure
  */
 static int64_t nuv_read_dts(AVFormatContext *s, int stream_index,
                             int64_t *ppos, int64_t pos_limit)
 {
     NUVContext *ctx = s->priv_data;
     AVIOContext *pb = s->pb;
     uint8_t hdr[HDRSIZE];
     nuv_frametype frametype;
     int size, key, idx;
     int64_t pos, dts;

     if (avio_seek(pb, *ppos, SEEK_SET) < 0)
         return AV_NOPTS_VALUE;

     if (!nuv_resync(s, pos_limit))
         return AV_NOPTS_VALUE;

     while (!avio_feof(pb) && avio_tell(pb) < pos_limit) {
         if (avio_read(pb, hdr, HDRSIZE) < HDRSIZE)
             return AV_NOPTS_VALUE;
         frametype = hdr[0];
         size = PKTSIZE(AV_RL32(&hdr[8]));
         switch (frametype) {
             case NUV_SEEKP:
                 break;
             case NUV_AUDIO:
             case NUV_VIDEO:
                 if (frametype == NUV_VIDEO) {
                     idx = ctx->v_id;
                     key = hdr[2] == 0;
                 } else {
                     idx = ctx->a_id;
                     key = 1;
                 }
                 if (stream_index == idx) {

                     pos = avio_tell(s->pb) - HDRSIZE;
                     dts = AV_RL32(&hdr[4]);

                     // TODO - add general support in av_gen_search, so it adds positions after reading timestamps
                     av_add_index_entry(s->streams[stream_index], pos, dts, size + HDRSIZE, 0,
                             key ? AVINDEX_KEYFRAME : 0);

                     *ppos = pos;
                     return dts;
                 }
             default:
                 avio_skip(pb, size);
                 break;
         }
     }
     return AV_NOPTS_VALUE;
 }


 AVInputFormat ff_nuv_demuxer = {
     .name           = "nuv",
     .long_name      = NULL_IF_CONFIG_SMALL("NuppelVideo"),
     .priv_data_size = sizeof(NUVContext),
     .read_probe     = nuv_probe,
     .read_header    = nuv_header,
     .read_packet    = nuv_packet,
     .read_timestamp = nuv_read_dts,
     .flags          = AVFMT_GENERIC_INDEX,
 };
	/*
	* NuppelVideo demuxer.
	* Copyright (c) 2006 Reimar Doeffinger
	*
	* 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
	*/

	#include "libavutil/channel_layout.h"
	#include "libavutil/imgutils.h"
	#include "libavutil/intreadwrite.h"
	#include "libavutil/intfloat.h"
	#include "avformat.h"
	#include "internal.h"
	#include "riff.h"

	static const AVCodecTag nuv_audio_tags[] = {
	{ AV_CODEC_ID_PCM_S16LE, MKTAG('R', 'A', 'W', 'A') },
	{ AV_CODEC_ID_MP3, MKTAG('L', 'A', 'M', 'E') },
	{ AV_CODEC_ID_NONE, 0 },
	};

	typedef struct NUVContext {
	int v_id;
	int a_id;
	int rtjpg_video;
	} NUVContext;

	typedef enum {
	NUV_VIDEO = 'V',
	NUV_EXTRADATA = 'D',
	NUV_AUDIO = 'A',
	NUV_SEEKP = 'R',
	NUV_MYTHEXT = 'X'
	} nuv_frametype;

	static int nuv_probe(const AVProbeData *p)
	{
	if (!memcmp(p->buf, "NuppelVideo", 12))
	return AVPROBE_SCORE_MAX;
	if (!memcmp(p->buf, "MythTVVideo", 12))
	return AVPROBE_SCORE_MAX;
	return 0;
	}

	/// little macro to sanitize packet size
	#define PKTSIZE(s) (s & 0xffffff)

	/**
	* @brief read until we found all data needed for decoding
	* @param vst video stream of which to change parameters
	* @param ast video stream of which to change parameters
	* @param myth set if this is a MythTVVideo format file
	* @return 0 or AVERROR code
	*/
	static int get_codec_data(AVFormatContext s, AVIOContext pb, AVStream *vst,
	AVStream *ast, int myth)
	{
	nuv_frametype frametype;

	if (!vst && !myth)
	return 1; // no codec data needed
	while (!avio_feof(pb)) {
	int size, subtype, ret;

	frametype = avio_r8(pb);
	switch (frametype) {
	case NUV_EXTRADATA:
	subtype = avio_r8(pb);
	avio_skip(pb, 6);
	size = PKTSIZE(avio_rl32(pb));
	if (vst && subtype == 'R') {
	if ((ret = ff_get_extradata(NULL, vst->codecpar, pb, size)) < 0)
	return ret;
	size = 0;
	if (!myth)
	return 0;
	}
	break;
	case NUV_MYTHEXT:
	avio_skip(pb, 7);
	size = PKTSIZE(avio_rl32(pb));
	if (size != 128 * 4)
	break;
	avio_rl32(pb); // version
	if (vst) {
	vst->codecpar->codec_tag = avio_rl32(pb);
	vst->codecpar->codec_id =
	ff_codec_get_id(ff_codec_bmp_tags, vst->codecpar->codec_tag);
	if (vst->codecpar->codec_tag == MKTAG('R', 'J', 'P', 'G'))
	vst->codecpar->codec_id = AV_CODEC_ID_NUV;
	} else
	avio_skip(pb, 4);

	if (ast) {
	int id;

	ast->codecpar->codec_tag = avio_rl32(pb);
	ast->codecpar->sample_rate = avio_rl32(pb);
	if (ast->codecpar->sample_rate <= 0) {
	av_log(s, AV_LOG_ERROR, "Invalid sample rate %d\n", ast->codecpar->sample_rate);
	return AVERROR_INVALIDDATA;
	}
	ast->codecpar->bits_per_coded_sample = avio_rl32(pb);
	ast->codecpar->channels = avio_rl32(pb);
	ast->codecpar->channel_layout = 0;

	id = ff_wav_codec_get_id(ast->codecpar->codec_tag,
	ast->codecpar->bits_per_coded_sample);
	if (id == AV_CODEC_ID_NONE) {
	id = ff_codec_get_id(nuv_audio_tags, ast->codecpar->codec_tag);
	if (id == AV_CODEC_ID_PCM_S16LE)
	id = ff_get_pcm_codec_id(ast->codecpar->bits_per_coded_sample,
	0, 0, ~1);
	}
	ast->codecpar->codec_id = id;

	ast->need_parsing = AVSTREAM_PARSE_FULL;
	} else
	avio_skip(pb, 4 * 4);

	size -= 6 * 4;
	avio_skip(pb, size);
	return 0;
	case NUV_SEEKP:
	size = 11;
	break;
	default:
	avio_skip(pb, 7);
	size = PKTSIZE(avio_rl32(pb));
	break;
	}
	avio_skip(pb, size);
	}

	return 0;
	}

	static int nuv_header(AVFormatContext *s)
	{
	NUVContext *ctx = s->priv_data;
	AVIOContext *pb = s->pb;
	char id_string[12];
	double aspect, fps;
	int is_mythtv, width, height, v_packs, a_packs, ret;
	AVStream vst = NULL, ast = NULL;

	avio_read(pb, id_string, 12);
	is_mythtv = !memcmp(id_string, "MythTVVideo", 12);
	avio_skip(pb, 5); // version string
	avio_skip(pb, 3); // padding
	width = avio_rl32(pb);
	height = avio_rl32(pb);
	avio_rl32(pb); // unused, "desiredwidth"
	avio_rl32(pb); // unused, "desiredheight"
	avio_r8(pb); // 'P' == progressive, 'I' == interlaced
	avio_skip(pb, 3); // padding
	aspect = av_int2double(avio_rl64(pb));
	if (aspect > 0.9999 && aspect < 1.0001)
	aspect = 4.0 / 3.0;
	fps = av_int2double(avio_rl64(pb));
	if (fps < 0.0f) {
	if (s->error_recognition & AV_EF_EXPLODE) {
	av_log(s, AV_LOG_ERROR, "Invalid frame rate %f\n", fps);
	return AVERROR_INVALIDDATA;
	} else {
	av_log(s, AV_LOG_WARNING, "Invalid frame rate %f, setting to 0.\n", fps);
	fps = 0.0f;
	}
	}

	// number of packets per stream type, -1 means unknown, e.g. streaming
	v_packs = avio_rl32(pb);
	a_packs = avio_rl32(pb);
	avio_rl32(pb); // text

	avio_rl32(pb); // keyframe distance (?)

	if (v_packs) {
	vst = avformat_new_stream(s, NULL);
	if (!vst)
	return AVERROR(ENOMEM);
	ctx->v_id = vst->index;

	ret = av_image_check_size(width, height, 0, s);
	if (ret < 0)
	return ret;

	vst->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
	vst->codecpar->codec_id = AV_CODEC_ID_NUV;
	vst->codecpar->width = width;
	vst->codecpar->height = height;
	vst->codecpar->bits_per_coded_sample = 10;
	vst->sample_aspect_ratio = av_d2q(aspect * height / width,
	10000);
	#if FF_API_R_FRAME_RATE
	vst->r_frame_rate =
	#endif
	vst->avg_frame_rate = av_d2q(fps, 60000);
	avpriv_set_pts_info(vst, 32, 1, 1000);
	} else
	ctx->v_id = -1;

	if (a_packs) {
	ast = avformat_new_stream(s, NULL);
	if (!ast)
	return AVERROR(ENOMEM);
	ctx->a_id = ast->index;

	ast->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
	ast->codecpar->codec_id = AV_CODEC_ID_PCM_S16LE;
	ast->codecpar->channels = 2;
	ast->codecpar->channel_layout = AV_CH_LAYOUT_STEREO;
	ast->codecpar->sample_rate = 44100;
	ast->codecpar->bit_rate = 2 * 2 * 44100 * 8;
	ast->codecpar->block_align = 2 * 2;
	ast->codecpar->bits_per_coded_sample = 16;
	avpriv_set_pts_info(ast, 32, 1, 1000);
	} else
	ctx->a_id = -1;

	if ((ret = get_codec_data(s, pb, vst, ast, is_mythtv)) < 0)
	return ret;

	ctx->rtjpg_video = vst && vst->codecpar->codec_id == AV_CODEC_ID_NUV;

	return 0;
	}

	#define HDRSIZE 12

	static int nuv_packet(AVFormatContext s, AVPacket pkt)
	{
	NUVContext *ctx = s->priv_data;
	AVIOContext *pb = s->pb;
	uint8_t hdr[HDRSIZE];
	nuv_frametype frametype;
	int ret, size;

	while (!avio_feof(pb)) {
	int copyhdrsize = ctx->rtjpg_video ? HDRSIZE : 0;
	uint64_t pos = avio_tell(pb);

	ret = avio_read(pb, hdr, HDRSIZE);
	if (ret < HDRSIZE)
	return ret < 0 ? ret : AVERROR(EIO);

	frametype = hdr[0];
	size = PKTSIZE(AV_RL32(&hdr[8]));

	switch (frametype) {
	case NUV_EXTRADATA:
	if (!ctx->rtjpg_video) {
	avio_skip(pb, size);
	break;
	}
	case NUV_VIDEO:
	if (ctx->v_id < 0) {
	av_log(s, AV_LOG_ERROR, "Video packet in file without video stream!\n");
	avio_skip(pb, size);
	break;
	}
	ret = av_new_packet(pkt, copyhdrsize + size);
	if (ret < 0)
	return ret;

	pkt->pos = pos;
	pkt->flags \|= hdr[2] == 0 ? AV_PKT_FLAG_KEY : 0;
	pkt->pts = AV_RL32(&hdr[4]);
	pkt->stream_index = ctx->v_id;
	memcpy(pkt->data, hdr, copyhdrsize);
	ret = avio_read(pb, pkt->data + copyhdrsize, size);
	if (ret < 0) {
	return ret;
	}
	if (ret < size)
	av_shrink_packet(pkt, copyhdrsize + ret);
	return 0;
	case NUV_AUDIO:
	if (ctx->a_id < 0) {
	av_log(s, AV_LOG_ERROR, "Audio packet in file without audio stream!\n");
	avio_skip(pb, size);
	break;
	}
	ret = av_get_packet(pb, pkt, size);
	pkt->flags \|= AV_PKT_FLAG_KEY;
	pkt->pos = pos;
	pkt->pts = AV_RL32(&hdr[4]);
	pkt->stream_index = ctx->a_id;
	if (ret < 0)
	return ret;
	return 0;
	case NUV_SEEKP:
	// contains no data, size value is invalid
	break;
	default:
	avio_skip(pb, size);
	break;
	}
	}

	return AVERROR(EIO);
	}

	/**
	* \brief looks for the string RTjjjjjjjjjj in the stream too resync reading
	* \return 1 if the syncword is found 0 otherwise.
	*/
	static int nuv_resync(AVFormatContext *s, int64_t pos_limit) {
	AVIOContext *pb = s->pb;
	uint32_t tag = 0;
	while(!avio_feof(pb) && avio_tell(pb) < pos_limit) {
	tag = (tag << 8) \| avio_r8(pb);
	if (tag == MKBETAG('R','T','j','j') &&
	(tag = avio_rb32(pb)) == MKBETAG('j','j','j','j') &&
	(tag = avio_rb32(pb)) == MKBETAG('j','j','j','j'))
	return 1;
	}
	return 0;
	}

	/**
	* \brief attempts to read a timestamp from stream at the given stream position
	* \return timestamp if successful and AV_NOPTS_VALUE if failure
	*/
	static int64_t nuv_read_dts(AVFormatContext *s, int stream_index,
	int64_t *ppos, int64_t pos_limit)
	{
	NUVContext *ctx = s->priv_data;
	AVIOContext *pb = s->pb;
	uint8_t hdr[HDRSIZE];
	nuv_frametype frametype;
	int size, key, idx;
	int64_t pos, dts;

	if (avio_seek(pb, *ppos, SEEK_SET) < 0)
	return AV_NOPTS_VALUE;

	if (!nuv_resync(s, pos_limit))
	return AV_NOPTS_VALUE;

	while (!avio_feof(pb) && avio_tell(pb) < pos_limit) {
	if (avio_read(pb, hdr, HDRSIZE) < HDRSIZE)
	return AV_NOPTS_VALUE;
	frametype = hdr[0];
	size = PKTSIZE(AV_RL32(&hdr[8]));
	switch (frametype) {
	case NUV_SEEKP:
	break;
	case NUV_AUDIO:
	case NUV_VIDEO:
	if (frametype == NUV_VIDEO) {
	idx = ctx->v_id;
	key = hdr[2] == 0;
	} else {
	idx = ctx->a_id;
	key = 1;
	}
	if (stream_index == idx) {

	pos = avio_tell(s->pb) - HDRSIZE;
	dts = AV_RL32(&hdr[4]);

	// TODO - add general support in av_gen_search, so it adds positions after reading timestamps
	av_add_index_entry(s->streams[stream_index], pos, dts, size + HDRSIZE, 0,
	key ? AVINDEX_KEYFRAME : 0);

	*ppos = pos;
	return dts;
	}
	default:
	avio_skip(pb, size);
	break;
	}
	}
	return AV_NOPTS_VALUE;
	}


	AVInputFormat ff_nuv_demuxer = {
	.name = "nuv",
	.long_name = NULL_IF_CONFIG_SMALL("NuppelVideo"),
	.priv_data_size = sizeof(NUVContext),
	.read_probe = nuv_probe,
	.read_header = nuv_header,
	.read_packet = nuv_packet,
	.read_timestamp = nuv_read_dts,
	.flags = AVFMT_GENERIC_INDEX,
	};