I'm trying to write mkv file using ffmpeg to encode in FFV1 and FLAC in NTSC format, but the frame rate shown in VLC and media info are not correct.
Here is how I create and configure the output format context:
AVOutputFormat *outputFormat = av_guess_format("matroska", NULL, NULL);
//Allocate an AVFormatContext for an output format.
int err = avformat_alloc_output_context2(&_formatContext, outputFormat, NULL, filename);
//Specify the codec of the outputFormat
_formatContext->oformat->video_codec = _videoCodecContext->codec_id;
//Create AVStream
AVStream *videoStream = avformat_new_stream(_formatContext, NULL);
//FrameDuration.value : 1001, FrameDuration.timescale : 30000
videoStream->time_base = (AVRational){ (int)_frameDuration.value, (int)_frameDuration.timescale }; //1001 30000
//Copy video stream parameters to the muxer
err = avcodec_parameters_from_context(videoStream->codecpar, _videoCodecContext);
//Open file for writing
err = avio_open(&_formatContext->pb, filename, AVIO_FLAG_WRITE);
if (err >= 0) {
//Write header
err = avformat_write_header(_formatContext, &options);
}
Before writing the packet, I use this to convert PTS to the stream time_base
// Rescale output packet timestamp values from codec to stream timebase
av_packet_rescale_ts(inAVPacket, *inTimeStamp, [outputStream stream]->time_base);
The thing is that the avformat_write_header method is changing the stream time_base from 30000/1001 to 1/1000, so PTS loose precision. In VLC inspector, the frame rate shown is 1000 fps and in MediaInfo 30.033 fps.
The file is playing correctly and the video/audio sync is OK.
Is there something to do to specify the file frame rate somewhere else ?
Or a work around to avoid changing the time_base when calling avformat_write_header ?
Setting the avg_frame_rate fixes the issue...
videoStream->avg_frame_rate = _videoCodecContext->framerate;
Related
I am trying to create a live RTMP stream containing the animation generated with NVIDIA OptiX. The stream is to be received by nginx + rtmp module and broadcasted in MPEG-DASH format. Full chain up to dash.js player is working if the video is first saved to .flv file and then I send it with ffmpeg without any reformatting using command:
ffmpeg -re -i my_video.flv -c:v copy -f flv rtmp://x.x.x.x:1935/dash/test
But I want to stream directly from the code. And with this I am failng... Nginx logs an error "dash: invalid avcc received (2: No such file or directory)". Then it seems to receive the stream correctly (segments are rolling, dash manifest is there), however the stream is not possible to play in the browser.
I can see only one difference in the manifest between direct stream and stream from file. Codecs attribute of the representation in the direct stream is missed: codecs="avcc1.000000" instead of "avc1.640028" which I get when streaming from file.
My code opens the stream:
av_register_all();
AVOutputFormat* fmt = av_guess_format("flv",
file_name, nullptr);
fmt->video_codec = AV_CODEC_ID_H264;
AVFormatContext* _oc;
avformat_alloc_output_context2(&_oc, fmt, nullptr, "rtmp://x.x.x.x:1935/dash/test");
AVStream* _vs = avformat_new_stream(_oc, nullptr);
_vs->id = 0;
_vs->time_base = AVRational { 1, 25 };
_vs->avg_frame_rate = AVRational{ 25, 1 };
AVCodecParameters *vpar = _vs->codecpar;
vpar->codec_id = fmt->video_codec;
vpar->codec_type = AVMEDIA_TYPE_VIDEO;
vpar->format = AV_PIX_FMT_YUV420P;
vpar->profile = FF_PROFILE_H264_HIGH;
vpar->level = _level;
vpar->width = _width;
vpar->height = _height;
vpar->bit_rate = _avg_bitrate;
avio_open(&_oc->pb, _oc->filename, AVIO_FLAG_WRITE);
avformat_write_header(_oc, nullptr);
Width, height, bitrate, level and profile I get from NVENC encoder settings. I also do the error checking, ommited here. Then I have a loop writing each encoded packets, with IDR frames etc all prepared on the fly with NVENC. The loop body is:
auto & pkt_data = _packets[i];
AVPacket pkt = { 0 };
av_init_packet(&pkt);
pkt.pts = av_rescale_q(_n_frames++, AVRational{ 1, 25 }, _vs->time_base);
pkt.duration = av_rescale_q(1, AVRational{ 1, 25 }, _vs->time_base);
pkt.dts = pkt.pts;
pkt.stream_index = _vs->index;
pkt.data = pkt_data.data();
pkt.size = (int)pkt_data.size();
if (!memcmp(pkt_data.data(), "\x00\x00\x00\x01\x67", 5))
{
pkt.flags |= AV_PKT_FLAG_KEY;
}
av_write_frame(_oc, &pkt);
Obviously ffmpeg is writing avcc code somewhere... I have no clue where to add this code so the RTMP server can recognize it. Or I am missing something else?
Any hint greatly appreciated, folks!
Thanks to Gyan's comment I was able to solve the issue. Following the AV_CODEC_FLAG_GLOBAL_HEADER flag in the wrapper one can see how the global header is added, which was missing in my case. You can use directly the NVENC API function nvEncGetSequenceParams, but since I am anyway using SDK, it is a bit cleaner.
So I had to attach the header to AVCodecParameters::extradata:
std::vector<uint8_t> payload;
_encoder->GetSequenceParams(payload);
vpar->extradata_size = payload.size();
vpar->extradata = (uint8_t*)av_mallocz(payload.size() + AV_INPUT_BUFFER_PADDING_SIZE);
memcpy(vpar->extradata, payload.data(), payload.size());
_encoder is my instance of NvEncoder from SDK.
The wrapper is doing the same thing, however using deprecated struct AVCodecContext.
I used FFmpeg library version 4.0 to have simple C++ program, in witch is a thread to receive RTSP H264 video data from IP-camera and display it in program window.
Code of this thread is follow:
DWORD WINAPI GrabbProcess(LPVOID lpParam)
// Grabbing thread
{
DWORD i;
int ret = 0, nPacket=0;
FILE *pktFile;
// Open video file
pFormatCtx = avformat_alloc_context();
if(avformat_open_input(&pFormatCtx, nameVideoStream, NULL, NULL)!=0)
fGrabb=-1; // Couldn't open file
else
// Retrieve stream information
if(avformat_find_stream_info(pFormatCtx, NULL)<0)
fGrabb=-2; // Couldn't find stream information
else
{
// Find the first video stream
videoStream=-1;
for(i=0; i<pFormatCtx->nb_streams; i++)
if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
{
videoStream=i;
break;
}
if(videoStream==-1)
fGrabb=-3; // Didn't find a video stream
else
{
// Get a pointer to the codec context for the video stream
pCodecCtxOrig=pFormatCtx->streams[videoStream]->codec;
// Find the decoder for the video stream
pCodec=avcodec_find_decoder(pCodecCtxOrig->codec_id);
if(pCodec==NULL)
fGrabb=-4; // Codec not found
else
{
// Copy context
pCodecCtx = avcodec_alloc_context3(pCodec);
if(avcodec_copy_context(pCodecCtx, pCodecCtxOrig) != 0)
fGrabb=-5; // Error copying codec context
else
{
// Open codec
if(avcodec_open2(pCodecCtx, pCodec, NULL)<0)
fGrabb=-6; // Could not open codec
else
// Allocate video frame for input
pFrame=av_frame_alloc();
// Determine required buffer size and allocate buffer
numBytes=avpicture_get_size(pCodecCtx->pix_fmt, pCodecCtx->width,
pCodecCtx->height);
buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
// Assign appropriate parts of buffer to image planes in pFrame
// Note that pFrame is an AVFrame, but AVFrame is a superset
// of AVPicture
avpicture_fill((AVPicture *)pFrame, buffer, pCodecCtx->pix_fmt,
pCodecCtx->width, pCodecCtx->height);
// Allocate video frame for display
pFrameRGB=av_frame_alloc();
// Determine required buffer size and allocate buffer
numBytes=avpicture_get_size(AV_PIX_FMT_RGB24, pCodecCtx->width,
pCodecCtx->height);
bufferRGB=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
// Assign appropriate parts of buffer to image planes in pFrameRGB
// Note that pFrameRGB is an AVFrame, but AVFrame is a superset
// of AVPicture
avpicture_fill((AVPicture *)pFrameRGB, bufferRGB, AV_PIX_FMT_RGB24,
pCodecCtx->width, pCodecCtx->height);
// initialize SWS context for software scaling to FMT_RGB24
sws_ctx_to_RGB = sws_getContext(pCodecCtx->width,
pCodecCtx->height,
pCodecCtx->pix_fmt,
pCodecCtx->width,
pCodecCtx->height,
AV_PIX_FMT_RGB24,
SWS_BILINEAR,
NULL,
NULL,
NULL);
// Allocate video frame (grayscale YUV420P) for processing
pFrameYUV=av_frame_alloc();
// Determine required buffer size and allocate buffer
numBytes=avpicture_get_size(AV_PIX_FMT_YUV420P, pCodecCtx->width,
pCodecCtx->height);
bufferYUV=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
// Assign appropriate parts of buffer to image planes in pFrameYUV
// Note that pFrameYUV is an AVFrame, but AVFrame is a superset
// of AVPicture
avpicture_fill((AVPicture *)pFrameYUV, bufferYUV, AV_PIX_FMT_YUV420P,
pCodecCtx->width, pCodecCtx->height);
// initialize SWS context for software scaling to FMT_YUV420P
sws_ctx_to_YUV = sws_getContext(pCodecCtx->width,
pCodecCtx->height,
pCodecCtx->pix_fmt,
pCodecCtx->width,
pCodecCtx->height,
AV_PIX_FMT_YUV420P,
SWS_BILINEAR,
NULL,
NULL,
NULL);
RealBsqHdr.biWidth = pCodecCtx->width;
RealBsqHdr.biHeight = -pCodecCtx->height;
}
}
}
}
while ((fGrabb==1)||(fGrabb==100))
{
// Grabb a frame
if (av_read_frame(pFormatCtx, &packet) >= 0)
{
// Is this a packet from the video stream?
if(packet.stream_index==videoStream)
{
// Decode video frame
int len = avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
nPacket++;
// Did we get a video frame?
if(frameFinished)
{
// Convert the image from its native format to YUV
sws_scale(sws_ctx_to_YUV, (uint8_t const * const *)pFrame->data,
pFrame->linesize, 0, pCodecCtx->height,
pFrameYUV->data, pFrameYUV->linesize);
// Convert the image from its native format to RGB
sws_scale(sws_ctx_to_RGB, (uint8_t const * const *)pFrame->data,
pFrame->linesize, 0, pCodecCtx->height,
pFrameRGB->data, pFrameRGB->linesize);
HDC hdc=GetDC(hWndM);
SetDIBitsToDevice(hdc, 0, 0, pCodecCtx->width, pCodecCtx->height,
0, 0, 0, pCodecCtx->height,pFrameRGB->data[0], (LPBITMAPINFO)&RealBsqHdr, DIB_RGB_COLORS);
ReleaseDC(hWndM,hdc);
av_frame_unref(pFrame);
}
}
// Free the packet that was allocated by av_read_frame
av_free_packet(&packet);
}
}
// Free the org frame
av_frame_free(&pFrame);
// Free the RGB frame
av_frame_free(&pFrameRGB);
// Free the YUV frame
av_frame_free(&pFrameYUV);
// Close the codec
avcodec_close(pCodecCtx);
avcodec_close(pCodecCtxOrig);
// Close the video file
avformat_close_input(&pFormatCtx);
avformat_free_context(pFormatCtx);
if (fGrabb==1)
sprintf(tmpstr,"Grabbing Completed %d frames", nCntTotal);
else if (fGrabb==2)
sprintf(tmpstr,"User break on %d frames", nCntTotal);
else if (fGrabb==3)
sprintf(tmpstr,"Can't Grabb at frame %d", nCntTotal);
else if (fGrabb==-1)
sprintf(tmpstr,"Couldn't open file");
else if (fGrabb==-2)
sprintf(tmpstr,"Couldn't find stream information");
else if (fGrabb==-3)
sprintf(tmpstr,"Didn't find a video stream");
else if (fGrabb==-4)
sprintf(tmpstr,"Codec not found");
else if (fGrabb==-5)
sprintf(tmpstr,"Error copying codec context");
else if (fGrabb==-6)
sprintf(tmpstr,"Could not open codec");
i=(UINT) fGrabb;
fGrabb=0;
SetWindowText(hWndM,tmpstr);
ExitThread(i);
return 0;
}
// End Grabbing thread
When program receive RTSP H264 video data with resolution 704x576 then decoded video pictures are OK. When receive RTSP H264 HD-video data with resolution 1280x720 it look like that first video picture is decoded OK and then video pictures are decoded but always with some error.
Please help me to fix this problem!
Here is problems brief :
I have an IP camera model HI3518E_50H10L_S39 (product of China).
Camera can provide H264 video stream both at resolution 704x576 (with RTSP URI "rtsp://192.168.1.18:554/user=admin_password=tlJwpbo6_channel=1_stream=1.sdp?real_stream") or 1280x720 (with RTSP URI "rtsp://192.168.1.18:554/user=admin_password=tlJwpbo6_channel=1_stream=0.sdp?real_stream").
Using FFplay utility I can access and display them with good picture quality.
For testing of grabbing from this camera, I have a simple (above mentioned) program in VC-2005. In "Grabbing thread" program use FFmpeg library version 4.0 for opening camera RTSP stream, retrieve stream information, find the first video stream... and prepare some variables.
Center of this thread is loop: Grab a frame (function av_read_frame) - Decode it if it's video (function avcodec_decode_video2) - Convert to RGB format (function sws_scale) - Display to program window (GDI function SetDIBitsToDevice).
When proram run with camera RTSP stream at resolution 704x576, I have good video picture. Here is a sample:
704x576 sample
When program run with camera RTSP stream at resolution 1280x720, first video picture is good:
First good at res.1280x720
but then not good:
not good at res.1280x720
Its seem to be my FFmpeg function call to avcodec_decode_video2 can't fully decode certain packet for some reasons.
I’m trying to transcode a video on my iOS app using FFMpeg/LibAv.
What I’m trying to accomplish is to transcode a video in order to resize each frame and possibly lower the bitrate in order to save valuable MB in the device.
The resulting video must be playable on all iPhone5+ devices.
After reading the documentation I found out that:
I do not need to encode/decode the audio stream -> I’ll copy as-is to the output file
I need to encode the video using the h264 codec (LibX264) with a profile supported by iOS (baseline profile with level 3.0 - https://trac.ffmpeg.org/wiki/Encode/H.264#Compatibility)
I’m also setting the picture format to YUV planar since it’s the only one supported by iOS
For the sake of testing I’m not using any filter (I’m using a dummy/passthrough) at all or even trying to lower the bitrate, I’m just trying to decode the video stream and encode it again
Most of the code is based on the transcoding.c and filtering.c available on the FFMpeg examples directory
FFMpeg-wise what I’m trying to achieve with LibAv is:
ffmpeg -i INPUT.MOV -c:v libx264 -preset ultrafast -profile:v baseline -level 3.0 -c:a copy output.MOV
(the resulting file - which can be found below - is playable on QuickTime if it’s generated by FFMpeg through the command line)
The original video was generated with a regular iPhone using iOS 8.2 but the problem is not device specific or iOS specific, it occurs on all videos generated with LibAv.
Although both resulting files are playable by VideoLan (VLC) the one I generated through LibAv is not playable by QuickTime even though I can’t find anything wrong with it.
As you can see below, I create the video stream with the proper video codec on the call to avformat_new_stream:
AVStream *out_stream; // output stream
AVStream *in_stream; // input stream
AVCodecContext *dec_ctx, *enc_ctx; // codec context for the stream
AVCodec *encoder; // codec used
int ret;
unsigned int i;
ofmt_ctx = NULL;
// Allocate an AVFormatContext for an output format. This will be the file header (similar to avformat_open_input but with an zero'ed memory)
avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, filename);
if (!ofmt_ctx) {
av_log(NULL, AV_LOG_ERROR, "Could not create output context\n");
[self errorWith:kErrorCreatingOutputContext and:#"Could not create output context"];
return AVERROR_UNKNOWN;
}
// we must not use the AVCodecContext from the video stream directly! So we have to use avcodec_copy_context() to copy the context to a new location (after allocating memory for it, of course).
// iterate over all input streams
for (i = 0; i < ifmt_ctx->nb_streams; i++) {
in_stream = ifmt_ctx->streams[i]; // input stream
dec_ctx = in_stream->codec; // get the codec context for the decoder
if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO) {
// lets use h264
encoder = avcodec_find_encoder(AV_CODEC_ID_H264);
if (!encoder) {
[self errorWith:kErrorCodecNotFound and:#"H264 Codec Not Found"];
return AVERROR_UNKNOWN;
}
out_stream = avformat_new_stream(ofmt_ctx, encoder); // create a new stream with h264 codec
if (!out_stream) {
av_log(NULL, AV_LOG_ERROR, "Failed allocating output stream\n");
[self errorWith:kErrorAllocateOutputStream and:#"Failed allocating output stream"];
return AVERROR_UNKNOWN;
}
enc_ctx = out_stream->codec; // pointer to the stream codec context
/* we transcode to same properties (picture size,
* sample rate etc.). These properties can be changed for output
* streams easily using filters */
if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO) {
enc_ctx->width = dec_ctx->width;
enc_ctx->height = dec_ctx->height;
enc_ctx->sample_aspect_ratio = dec_ctx->sample_aspect_ratio;
enc_ctx->pix_fmt = AV_PIX_FMT_YUV420P;
enc_ctx->time_base = dec_ctx->time_base;
av_opt_set(enc_ctx->priv_data, "preset", "ultrafast", 0);
av_opt_set(enc_ctx->priv_data, "profile", "baseline", 0);
av_opt_set(enc_ctx->priv_data, "level", "3.0", 0);
}
out_stream->time_base = in_stream->time_base;
AVDictionaryEntry *tag = NULL;
while ((tag = av_dict_get(in_stream->metadata, "", tag, AV_DICT_IGNORE_SUFFIX))) {
printf("%s=%s\n", tag->key, tag->value);
char *k = av_strdup(tag->key); // if your strings are already allocated,
char *v = av_strdup(tag->value); // you can avoid copying them like this
av_dict_set(&out_stream->metadata, k, v, 0);
}
ret = avcodec_open2(enc_ctx, encoder, NULL);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Cannot open video encoder for stream #%u\n", i);
[self errorWith:kErrorCantOpenOutputFile and:[NSString stringWithFormat:#"Cannot open video encoder for stream #%u",i]];
return ret;
}
}
else if(dec_ctx->codec_type == AVMEDIA_TYPE_UNKNOWN) {
// if we cant figure out the stream type, fail
av_log(NULL, AV_LOG_FATAL, "Elementary stream #%d is of unknown type, cannot proceed\n", i);
[self errorWith:kErrorUnknownStream and:[NSString stringWithFormat:#"Elementary stream #%d is of unknown type, cannot proceed",i]];
return AVERROR_INVALIDDATA;
}
else {
out_stream = avformat_new_stream(ofmt_ctx, NULL);
if (!out_stream) {
av_log(NULL, AV_LOG_ERROR, "Failed allocating output stream\n");
[self errorWith:kErrorAllocateOutputStream and:#"Failed allocating output stream"];
return AVERROR_UNKNOWN;
}
enc_ctx = out_stream->codec;
/* this stream must be remuxed */
// copies ifmt_ctx->streams[i]->codec into ofmt_ctx->streams[i]->codec - Copy the settings of the source AVCodecContext into the destination AVCodecContext.
ret = avcodec_copy_context(ofmt_ctx->streams[i]->codec,
ifmt_ctx->streams[i]->codec);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Copying stream context failed\n");
[self errorWith:kErrorCopyStreamFailed and:#"Copying stream context failed"];
return ret;
}
}
// dunno what this is for
if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
enc_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
}
if (!(ofmt_ctx->oformat->flags & AVFMT_NOFILE)) {
// Create and initialize a AVIOContext for accessing the
// resource indicated by url.
ret = avio_open(&ofmt_ctx->pb, filename, AVIO_FLAG_WRITE);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Could not open output file '%s'", filename);
[self errorWith:kErrorCantOpenOutputFile and:[NSString stringWithFormat:#"Could not open output file '%s'", filename]];
return ret;
}
}
/* init muxer, write output file header */
// Allocate the stream private data and write the stream header to an output media file.
ret = avformat_write_header(ofmt_ctx, NULL);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Error occurred when opening output file\n");
[self errorWith:kErrorOutFileCantWriteHeader and:#"Error occurred when opening output file"];
return ret;
}
return 0;
You can find the files here:
Original final: https://www.dropbox.com/s/2jjs1uy2pu2veyy/IMG_5705.MOV?dl=0
File generated with FFMpeg - https://www.dropbox.com/s/9hfmq3fcifgpfqc/local-ffmpeg.MOV?dl=0
File generated by code - https://www.dropbox.com/s/rttvny39rj7ejpf/generated-by-Ze.MOV?dl=0
Thank you so much,
Ze
I am using FFMpeg To decode live video and stream it using Live555.i am able to decode video and getting the output AVPackets.
1. Convert the BGR Image to YUV422P format using FFMpeg's SWScale
// initilize a BGR To RGB converter using FFMpeg
ctx = sws_getContext(codecContext->width, codecContext->height, AV_PIX_FMT_BGR24, codecContext->width, codecContext->height, AV_PIX_FMT_YUV422P, SWS_BICUBIC, 0, 0, 0);
tempFrame = av_frame_alloc();
int num_bytes = avpicture_get_size(PIX_FMT_BGR24, codecContext->width, codecContext->height);
uint8_t* frame2_buffer = (uint8_t*)av_malloc(num_bytes*sizeof(uint8_t));
avpicture_fill((AVPicture*)tempFrame, frame2_buffer, PIX_FMT_BGR24, codecContext->width, codecContext->height);
// inside the loop of where frames are being encoded where rawFrame is a BGR image
tempFrame->data[0] = reinterpret_cast<uint8_t*>(rawFrame->_data);
sws_scale(ctx, tempFrame->data, tempFrame->linesize, 0, frame->height, frame->data, frame->linesize);
For decoding each Frame
ret = avcodec_encode_video2(codecContext, &packet, frame, &got_output);
if(ret < 0)
{
fprintf(stderr, "Error in encoding frame\n");
exit(1);
}
if(got_output)
{
//printf("Received frame! pushing to queue\n");
OutputFrame *outFrame = new OutputFrame();
outFrame->_data = packet.buf->data;
outFrame->_bufferSize = packet.buf->size;
outputQueue.push_back(outFrame);
}
Till here it works fine. i am able to write these frames to file and play it using VLC. after this i have to pass the output frame to Live555.i think AVPackets i am getting here doesn't need to be a single H264 Nal unit which is required by Live555.
How to break a AVPacket into Nal units which can be passed to Live555?
H264VideoStreamDiscreateFramer expect data without the start code '\x00\x00\x00\x01'.
It is needed to remove the 4 first bytes either in your LiveDeviceSource or inserting a FramedFilter to do this job.
Perhaps you can tried to use an H264VideoStreamFramer, like the testH264VideoStreamer test program.
If it could help, you can find one of my tries with live555 implementing an RTSP server feed from V4L2 capture https://github.com/mpromonet/h264_v4l2_rtspserver
I want to realize an application that firstly decode a multi-media file(such as test.mp4 file, video codec id is H264), get a video stream and an audio stream, then make some different in the audio stream, at last encode the video stream(use libx264) and audio stream into a result file(result.mp4). To promote the efficiency, i omitted the decode and encode of video stream, i get the video packet via function "av_read_frame", then output it directly into the result file via function "av_write_frame". But there is no picture in the output file, and the size of output file is fairly small.
I tracked the ffmpeg code and found that in the function "av_write_frame->mov_write_packet->ff_mov_write_packet", it will call function "ff_avc_parse_nal_units" to obtain the size of nal unit, but the return value is very small(such as 208 bytes).
I find that the H264 stream in the MP4 file is not stored in Annex-B format, so it can't find start code(0x000001）， now my problem is how can I change the H264 stream to Annex-B format, and make it work?
I added start code at the beginning of every frame manually, but it still not work.
Anyone can give me any hint?Thanks very much.
Following is the codes similar with my:
// write the stream header, if any
av_write_header(pFormatCtxEnc);
.........
/**
* Init of Encoder and Decoder
*/
bool KeyFlag = false;
bool KeyFlagEx = false;
// Read frames and save frames to disk
int iPts = 1;
av_init_packet(&packet);
while(av_read_frame(pFormatCtxDec, &packet)>=0)
{
if (packet.flags == 1)
KeyFlag = true;
if (!KeyFlag)
continue;
if (m_bStop)
{
break;
}
// Is this a packet from the video stream?
if(packet.stream_index == videoStream)
{
currentframeNum ++;
if (progressCB != NULL && currentframeNum%20 == 0)
{
float fpercent = (float)currentframeNum/frameNum;
progressCB(fpercent,m_pUser);
}
if (currentframeNum >= beginFrame && currentframeNum <= endFrane)
{
if (packet.flags == 1)
KeyFlagEx = true;
if (!KeyFlagEx)
continue;
packet.dts = iPts ++;
av_write_frame(pFormatCtxEnc, &packet);
}
}
// Free the packet that was allocated by av_read_frame
}
// write the trailer, if any
av_write_trailer(pFormatCtxEnc);
/**
* Release of encoder and decoder
*/
return true;
You might try this: libavcodec/h264_mp4toannexb_bsf.c. It converts bitstream without start codes to bitstream with start codes.
Using your source file, does ffmpeg -i src.mp4 -vcodec copy -an dst.mp4 work? Does it work if you add -bsf h264_mp4toannexb? (all using the same version/build of ffmpeg as you are trying to use programmatically of course)