我正在尝试通过CCTV摄像头的SDK API收到的数据包将视频复制到mp4文件。来自CCTV的流似乎只包含h264 I和P帧的数据包（没有B帧）。
问题是，当我将AVCodecContext :: extradata留空时，文件在Daum PotPlayer中无法播放，但是，我可以在VLC中播放该文件。如果我提供额外的数据（可能不正确 - 我只是从HW编码器收到的数据包中复制前50个字节），该文件可以在PotPlayer中播放，但不能在VLC中播放。
我不知道，如何正确准备extradata。
下面的代码显示了多路复用。
void WriteVideo()
{
AVFormatContext* formatContext = nullptr;
AVStream* stream = nullptr;
int ret = 0;
ret = avformat_alloc_output_context2(&formatContext, nullptr, "mp4", OUTPUT_V_FILE_NAME);
if (ret < 0)
{
fprintf(stderr, "Error occurred when allocating output context: %d\n", ret);
return;
}
stream = avformat_new_stream(formatContext, nullptr);
if (!stream)
{
avformat_free_context(formatContext);
formatContext = nullptr;
fprintf(stderr, "Error occurred creating new stream");
return;
}
stream->codec->codec_tag = 0;
if (formatContext->oformat->flags & AVFMT_GLOBALHEADER)
{
stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
}
stream->codec->codec_type = AVMEDIA_TYPE_VIDEO;
stream->codec->codec_id = AV_CODEC_ID_H264;
stream->codec->pix_fmt = AV_PIX_FMT_YUV420P;
stream->codec->bit_rate = 4096000; // 8192000; // 4096000; // 384000;
stream->codec->width = 1920; // 352
stream->codec->height = 1080; // 288
stream->codec->gop_size = 50;
AVRational tb;
tb.num = 1;
tb.den = 25;
stream->codec->time_base = tb;
//stream->codec->field_order = AVFieldOrder::AV_FIELD_UNKNOWN;
//stream->codec->color_primaries = AVColorPrimaries::AVCOL_PRI_BT470BG;
//stream->codec->color_trc = AVColorTransferCharacteristic::AVCOL_TRC_GAMMA22;
//stream->codec->colorspace = AVColorSpace::AVCOL_SPC_BT470BG;
//stream->codec->chroma_sample_location = AVChromaLocation::AVCHROMA_LOC_CENTER;
AVRational aratio;
aratio.num = 1;
aratio.den = 1;
stream->codec->sample_aspect_ratio = aratio;
// stream->codec->delay = 0;
// stream->codec->color_range = AVColorRange::AVCOL_RANGE_MPEG;
av_dump_format(formatContext, 0, formatContext->filename, 1);
if (!(formatContext->oformat->flags & AVFMT_NOFILE))
{
if (avio_open(&formatContext->pb, formatContext->filename, AVIO_FLAG_WRITE) < 0)
{
avformat_free_context(formatContext);
formatContext = nullptr;
fprintf(stderr, "Error occurred when opening output file.");
return;
}
}
avformat_write_header(formatContext, nullptr);
int frameIdx = 0;
int pts = 0;
int dts = 0;
int pkt_pos = 0;
int size = static_cast<int>(tmpRawFrameBuffer.size());
AVPacket pkt = { 0 };
av_init_packet(&pkt);
while (frameIdx < size)
{
pkt.data = tmpRawFrameBuffer[frameIdx];
pkt.size = tmpRawFrameSizes[frameIdx];
// debug purphose start
FILE* f;
char filename[MAX_PATH];
sprintf_s(filename, MAX_PATH, OUTPUT_PACKET_FILE_PATTERN_NAME, frameIdx);
auto err = fopen_s(&f, filename, "wb");
if (err != 0)
{
fprintf(stderr, "Could not open %s\n", OUTPUT_V_FILE_NAME);
exit(1);
}
fflush(stdout);
fwrite(pkt.data, 1, pkt.size, f);
fclose(f);
// debug purphose end
if (tmpRawFrameTypes[frameIdx] == VIDEO_I_FRAME)
{
pkt.flags |= AV_PKT_FLAG_KEY;
stream->codec->extradata_size = 50;
stream->codec->extradata = (uint8_t*)av_malloc(stream->codec->extradata_size);
memcpy(stream->codec->extradata, pkt.data, stream->codec->extradata_size);
}
pkt.pts = pts++;
pkt.dts = dts++;
/* rescale output packet timestamp values from codec to stream timebase */
// av_packet_rescale_ts(&pkt, stream->codec->time_base, stream->time_base);
pkt.pts = av_rescale_q(pkt.pts, stream->codec->time_base, stream->time_base);
pkt.dts = av_rescale_q(pkt.dts, stream->codec->time_base, stream->time_base);
pkt.duration = 512; // should be calculated (derived from FPS 25, and 12800)
pkt.pos = -1;
pkt.stream_index = stream->index;
auto ret = av_write_frame(formatContext, &pkt);
if (ret < 0)
{
fprintf(stderr, "Error while writing video frame: %d\n", ret);
break;
}
av_packet_unref(&pkt);
++frameIdx;
}
if (formatContext)
{
av_write_trailer(formatContext);
if (!(formatContext->oformat->flags & AVFMT_NOFILE)) avio_close(formatContext->pb); // close the output file
avformat_free_context(formatContext);
formatContext = nullptr;
}
}
看来，来自摄像头的数据包（缓存在tmpRawFrameBuffer向量中）包含一些标题，但我无法解析它们，我不明白标题的含义。
I帧数据包的第一个字节看起来像转储：
00 00 01 FC 02 19 F0 87 A0 23 73 41 B6 C0 01 00
00 00 00 01 67 4D 00 2A 95 A8 1E 00 89 F9 61 00
00 03 00 01 00 00 03 00 32 84 00 00 00 01 68 EE
3C 80 00 00 00 01 06 E5 01 19 80 00 00 00 01 65
B8 00 00 08 C7 B0 23 FF F7 80 EE FE 63 B6 FB F5
...
第一个P帧的第一个字节：
00 00 01 FD E5 24 00 00 00 00 00 01 61 E0 22 27
FF D6 B0 D7 A4 2B 71 6B 19 C5 87 CA BB 8B BF 60
14 59 B4 00 CC BC 0F C0 9E FD 84 B5 FB C4 83 DB
5A 8B 80 FC EC D6 33 6D DE 10 96 6F 31 41 86 5C
D4 22 F9 33 48 5B CE 77 38 17 0C D6 DD C7 6C E8
...
下一个P帧的第一个字节：
00 00 01 FD 5E 2F 00 00 00 00 00 01 61 E0 42 2F
FF E7 06 DD 3C 66 26 15 94 93 7A F1 30 8A 6D B8
AD DD 6B 0F 38 89 1D 1B 5C AC 44 6A D7 D1 21 3B
E2 29 F8 14 BB 98 1C 06 4D B6 10 BB DB B9 CA 4F
0B ED B1 A9 06 78 8C EC 06 6D 9F 4F 79 0C 35 5B
...
...
开始下一个I帧：
00 00 01 FC 02 19 F0 87 A2 23 73 41 75 89 01 00
00 00 00 01 67 4D 00 2A 95 A8 1E 00 89 F9 61 00
00 03 00 01 00 00 03 00 32 84 00 00 00 01 68 EE
3C 80 00 00 00 01 06 E5 01 1B 80 00 00 00 01 65
B8 00 00 0F 07 F0 7F F6 6C 69 43 0F F0 28 DF 97
...
有人知道，如何正确填写extradata？我刚刚制作了前50个字节的副本，但看起来，这是不正确的。
标题可能是（AUD）（SPS）（PPS）（I-Slice）（PPS）（P-Slice）（PPS）（P-Slice）...（AUD）（SPS）（PPS）（ I-Slice）（https://stackoverflow.com/a/20686267/1699328）但是，我不知道，如何为
提取数据stream->codec->extradata
我试图在这篇文章H.264 muxed to MP4 using libavformat not playing back中获得一些灵感，但我无法弄清楚spsFrameLen，ppsFrameLen和spsFrame的值是什么。
muxer的结果（mp4文件的第一个和最后一个字节）：
00 00 00 20 66 74 79 70 69 73 6F 6D 00 00 02 00
69 73 6F 6D 69 73 6F 32 61 76 63 31 6D 70 34 31
00 00 00 08 66 72 65 65 00 26 2E 6D 6D 64 61 74
00 00 00 0D FC 02 19 F0 87 A0 23 73 41 B6 C0 01
00 00 00 00 16 67 4D 00 2A 95 A8 1E 00 89 F9 61
00 00 03 00 01 00 00 03 00 32 84 00 00 00 04 68
EE 3C 80 00 00 00 05 06 E5 01 19 80 00 01 C0 87
65 B8 00 00 08 C7 B0 23 FF F7 80 EE FE 63 B6 FB
F5 97 A8 6B 48 39 61 99 FD 99 27 41 F2 78 54 EE
D1 38 8E E8 18 DD 05 E4 BA F4 EB 69 CF 91 5C 34
...
...
...
95 B8 D8 D4 C3 AF A1 BA AC 28 F0 D4 D4 7C 48 9A
0C A6 8C 4C 98 00 00 05 1E 6D 6F 6F 76 00 00 00
6C 6D 76 68 64 00 00 00 00 00 00 00 00 00 00 00
00 00 00 03 E8 00 00 13 B0 00 01 00 00 01 00 00
00 00 00 00 00 00 00 00 00 00 01 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 01 00 00 00 00 00
00 00 00 00 00 00 00 00 00 40 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 02 00 00 04 48 74 72 61
6B 00 00 00 5C 74 6B 68 64 00 00 00 03 00 00 00
00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 13
B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00
00 40 00 00 00 07 80 00 00 04 38 00 00 00 00 00
24 65 64 74 73 00 00 00 1C 65 6C 73 74 00 00 00
00 00 00 00 01 00 00 13 B0 00 00 00 00 00 01 00
00 00 00 03 C0 6D 64 69 61 00 00 00 20 6D 64 68
64 00 00 00 00 00 00 00 00 00 00 00 00 00 00 32
00 00 00 FC 00 55 C4 00 00 00 00 00 2D 68 64 6C
72 00 00 00 00 00 00 00 00 76 69 64 65 00 00 00
00 00 00 00 00 00 00 00 00 56 69 64 65 6F 48 61
6E 64 6C 65 72 00 00 00 03 6B 6D 69 6E 66 00 00
00 14 76 6D 68 64 00 00 00 01 00 00 00 00 00 00
00 00 00 00 00 24 64 69 6E 66 00 00 00 1C 64 72
65 66 00 00 00 00 00 00 00 01 00 00 00 0C 75 72
6C 20 00 00 00 01 00 00 03 2B 73 74 62 6C 00 00
00 93 73 74 73 64 00 00 00 00 00 00 00 01 00 00
00 83 61 76 63 31 00 00 00 00 00 00 00 01 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 07 80
04 38 00 48 00 00 00 48 00 00 00 00 00 00 00 01
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 18 FF FF 00 00 00 2D 61 76 63 43 01 4D 00 2A
FF E1 00 16 67 4D 00 2A 95 A8 1E 00 89 F9 61 00
00 03 00 01 00 00 03 00 32 84 01 00 04 68 EE 3C
80 00 00 00 18 73 74 74 73 00 00 00 00 00 00 00
01 00 00 00 7E 00 00 02 00 00 00 00 1C 73 74 73
73 00 00 00 00 00 00 00 03 00 00 00 01 00 00 00
33 00 00 00 65 00 00 00 34 73 74 73 63 00 00 00
00 00 00 00 03 00 00 00 01 00 00 00 3B 00 00 00
01 00 00 00 02 00 00 00 37 00 00 00 01 00 00 00
03 00 00 00 0C 00 00 00 01 00 00 02 0C 73 74 73
7A 00 00 00 00 00 00 00 00 00 00 00 7E 00 01 C0
C7 00 00 24 EE 00 00 2F 67 00 00 1D 83 00 00 2E
8F 00 00 30 B6 00 00 2F 44 00 00 2F 50 00 00 34
6B 00 00 30 BE 00 00 31 0C 00 00 31 E7 00 00 30
EA 00 00 31 4E 00 00 31 A8 00 00 32 21 00 00 31
E6 00 00 31 B5 00 00 31 14 00 00 31 AF 00 00 31
9D 00 00 33 60 00 00 32 11 00 00 32 4C 00 00 31
F0 00 00 32 91 00 00 43 43 00 00 44 29 00 00 44
EC 00 00 44 20 00 00 44 86 00 00 45 AD 00 00 47
47 00 00 46 9F 00 00 46 D9 00 00 47 BE 00 00 48
CD 00 00 3E 50 00 00 40 98 00 00 41 0E 00 00 40
43 00 00 41 07 00 00 41 BB 00 00 41 FF 00 00 30
5E 00 00 33 C7 00 00 34 B7 00 00 33 F1 00 00 33
0D 00 00 32 DB 00 01 89 86 00 00 3B E1 00 00 3C
55 00 00 3C 64 00 00 3C B7 00 00 3C FD 00 00 3E
54 00 00 3E C5 00 00 3E 1C 00 00 3E 94 00 00 3E
44 00 00 3E D7 00 00 3F CC 00 00 3E D6 00 00 40
00 00 00 40 4D 00 00 40 04 00 00 3F A9 00 00 40
82 00 00 41 0F 00 00 41 64 00 00 41 E5 00 00 42
1E 00 00 42 2C 00 00 42 80 00 00 42 4D 00 00 43
9F 00 00 43 DA 00 00 44 45 00 00 44 21 00 00 44
B7 00 00 45 22 00 00 45 E3 00 00 45 BF 00 00 46
18 00 00 47 4B 00 00 45 05 00 00 47 34 00 00 46
60 00 00 46 97 00 00 46 66 00 00 46 29 00 00 46
38 00 00 47 1D 00 00 47 42 00 00 47 18 00 00 47
13 00 00 46 52 00 00 47 48 00 00 46 F8 00 01 BE
E3 00 00 3F 56 00 00 3B 32 00 00 38 F8 00 00 37
56 00 00 36 2D 00 00 35 DA 00 00 34 6B 00 00 3E
BE 00 00 3E B5 00 00 3F 33 00 00 3F AC 00 00 3F
38 00 00 42 32 00 01 1B DC 00 01 80 50 00 01 14
06 00 00 C2 BB 00 00 96 12 00 00 6D EC 00 00 54
E6 00 00 3A AC 00 00 32 00 00 00 2F 0A 00 00 2D
F1 00 00 1B 7F 00 00 00 1C 73 74 63 6F 00 00 00
00 00 00 00 03 00 00 00 30 00 0F DD AB 00 1F 7D
9E 00 00 00 62 75 64 74 61 00 00 00 5A 6D 65 74
61 00 00 00 00 00 00 00 21 68 64 6C 72 00 00 00
00 00 00 00 00 6D 64 69 72 61 70 70 6C 00 00 00
00 00 00 00 00 00 00 00 00 2D 69 6C 73 74 00 00
00 25 A9 74 6F 6F 00 00 00 1D 64 61 74 61 00 00
00 01 00 00 00 00 4C 61 76 66 35 37 2E 32 33 2E
31 30 30
非常感谢任何建议。
答案 0 :(得分：2)
首先，有些数据不属于视频流。你需要弄清楚如何删除它。其他所有内容都可以在这里得到解答：Possible Locations for Sequence/Picture Parameter Set(s) for H.264 Stream