static int yop_read_header(AVFormatContext *s) { YopDecContext *yop = s->priv_data; AVIOContext *pb = s->pb; AVCodecContext *audio_dec, *video_dec; AVStream *audio_stream, *video_stream; int frame_rate, ret; audio_stream = avformat_new_stream(s, NULL); video_stream = avformat_new_stream(s, NULL); // Extra data that will be passed to the decoder video_stream->codec->extradata_size = 8; video_stream->codec->extradata = av_mallocz(video_stream->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE); if (!video_stream->codec->extradata) // Audio audio_dec = audio_stream->codec; audio_dec->codec_type = AVMEDIA_TYPE_AUDIO; audio_dec->codec_id = AV_CODEC_ID_ADPCM_IMA_APC; audio_dec->channels = 1; audio_dec->sample_rate = 22050; // Video video_dec = video_stream->codec; video_dec->codec_type = AVMEDIA_TYPE_VIDEO; video_dec->codec_id = AV_CODEC_ID_YOP; avio_skip(pb, 6); frame_rate = avio_r8(pb); yop->frame_size = avio_r8(pb) * 2048; video_dec->width = avio_rl16(pb); video_dec->height = avio_rl16(pb); video_stream->sample_aspect_ratio = (AVRational){1, 2}; ret = avio_read(pb, video_dec->extradata, 8); if (ret < 8) return ret < 0 ? ret : AVERROR_EOF; yop->palette_size = video_dec->extradata[0] * 3 + 4; yop->audio_block_length = AV_RL16(video_dec->extradata + 6); // 1840 samples per frame, 1 nibble per sample; hence 1840/2 = 920 if (yop->audio_block_length < 920 || yop->audio_block_length + yop->palette_size >= yop->frame_size) { av_log(s, AV_LOG_ERROR, "YOP has invalid header\n"); return AVERROR_INVALIDDATA; } avio_seek(pb, 2048, SEEK_SET); avpriv_set_pts_info(video_stream, 32, 1, frame_rate); return 0; }