[Libav-user] A very mysterious question about FFMpeg encoding.
Denis
info at denisgottardello.it
Thu Sep 22 23:02:52 CEST 2011
> You need to show the source of your data. How do you get the frames from a
> webcam, does it come in packets? RGB data? that's the code you should show.
> The problem that I'm seeing is that you're using an avio context when you
> don't actually intend to write data with it to a file. Just take the webcam
> frame data call avcodec_encode_video and that function writes it to a
> buffer. I'm not sure why you're making the all these avio calls. I suggest
> you also look at the headers for avcodec_encode_video.
The source code is below. Can you explain me which are the steps that I must
follow?
void QThCamera::run() {
qDebug() << "QThCamera::run() start";
QString MPGFileName= "http://localhost:3000/a.mp4";
CvCapture *Capture= NULL;
Capture= cvCreateCameraCapture(Index, Width, Height);
if (!Capture) qDebug() << "cvCreateCameraCapture Error!";
else {
if (ExternalFrame) cvNamedWindow("Frame", CV_WINDOW_AUTOSIZE);
IplImage *frame= 0;
CvFont font;
cvInitFont(&font, CV_FONT_HERSHEY_SIMPLEX, 0.5f, 0.5f);
AVOutputFormat *pOutputFormat= av_guess_format("mp4", NULL, NULL); //
CODEC_ID_H264 -> mp4, CODEC_ID_THEORA -> ogg, CODEC_ID_MPEG4 -> mpegts,
CODEC_ID_VP8 -> webm
if (!pOutputFormat) {
qDebug() << "Could not set output format, using MPEG.";
pOutputFormat= av_guess_format("mpeg", NULL, NULL);
}
if (!pOutputFormat) qDebug() << "av_guess_format Error!";
else {
AVFormatContext *pFormatCtx;
if (avformat_alloc_output_context2(&pFormatCtx, pOutputFormat,
NULL, NULL)< 0) qDebug() << "avformat_alloc_output_context2 Error!";
else {
AVStream *pVideoStream= av_new_stream(pFormatCtx, 0);
if (!pVideoStream) qDebug() << "av_new_stream Error!";
else {
AVCodecContext *pCodecCtx= pVideoStream->codec;
pCodecCtx->codec_id= CODEC_ID_H264;
pCodecCtx->codec_type= AVMEDIA_TYPE_VIDEO;
pCodecCtx->bit_rate= 40000;
pCodecCtx->width= Width;
pCodecCtx->height= Height;
pCodecCtx->time_base.den= 25;
pCodecCtx->time_base.num= 1;
pCodecCtx->gop_size= 10;
pCodecCtx->pix_fmt= PIX_FMT_YUV420P;
if (pFormatCtx->oformat->flags & AVFMT_GLOBALHEADER)
pCodecCtx->flags |= CODEC_FLAG_GLOBAL_HEADER;
av_dump_format(pFormatCtx, 0, NULL, 1);
AVCodec *pCodec= avcodec_find_encoder(pCodecCtx-
>codec_id);
if (!pCodec) qDebug() << "avcodec_find_encoder Error!";
else {
if (avcodec_open(pCodecCtx, pCodec)< 0) qDebug() <<
"avcodec_open Error!";
else {
/*QFMPGFileOut.setFileName(MPGFileName);
if (QFMPGFileOut.open(QIODevice::WriteOnly)) {*/
if (avio_open(&pFormatCtx->pb,
MPGFileName.toStdString().c_str(), AVIO_FLAG_WRITE)< 0) qDebug() << "avio_open
Error!";
else {
/*pFormatCtx->pb->opaque= this;
pFormatCtx->pb->write_packet= WritePacket;
pFormatCtx->pb->write_flag=
AVIO_FLAG_WRITE;*/
if (avformat_write_header(pFormatCtx,
NULL)!= 0) qDebug() << "av_write_header Error!";
int BYTEPIC= Width * Height * 3;
uint8_t *pOutBuffer=
(uint8_t*)malloc(BYTEPIC); {
int Frames= 0;
QDateTime QDTStart=
QDateTime::currentDateTime();
while (DoStart) {
if (!cvSetChannel(Capture,
Channel)) qDebug() << "cvSetChannel Error!";
frame= cvQueryFrame(Capture);
if (frame) {
if (MainForm->ui-
>QCBAutoBrightness->isChecked()) {
int Brightness=
BrightnessOfAPixel(frame);
Brightness= ((Brightness *
200 / 256) - 100) * -1;
IplImage *frame2=
ContrastBrightness(frame, 0, Brightness); {
cvCopyImage(frame2,
frame);
}{
cvReleaseImage(&frame2);
}
} else {
IplImage *frame2=
ContrastBrightness(frame, MainForm->ui->QHSContrast->value(), MainForm->ui-
>QHSBrightness->value()); {
cvCopyImage(frame2,
frame);
}{
cvReleaseImage(&frame2);
}
}
if (MainForm->ui-
>QCBShowDateTime->isChecked()) cvPutText(frame,
QDateTime::currentDateTime().toString("dd-MM-yyyy hh:mm:ss").toAscii(),
cvPoint(10, 20), &font, cvScalar(255, 255, 255));
if (MainForm->ui->QRBRotate90-
>isChecked()) {
IplImage *frame2=
Rotate(frame, 90); {
cvCopyImage(frame2,
frame);
}{
cvReleaseImage(&frame2);
}
} else if (MainForm->ui-
>QRBRotate180->isChecked()) {
IplImage *frame2=
Rotate(frame, 180); {
cvCopyImage(frame2,
frame);
}{
cvReleaseImage(&frame2);
}
} else if (MainForm->ui-
>QRBRotate270->isChecked()) {
IplImage *frame2=
Rotate(frame, 270); {
cvCopyImage(frame2,
frame);
}{
cvReleaseImage(&frame2);
}
}
if (ExternalFrame)
cvShowImage("Frame", frame);
QImage Image(frame->width,
frame->height, QImage::Format_RGB888);
const unsigned char *data=
NULL;
data= (unsigned char*)(frame-
>imageData);
Image= QImage(data, frame-
>width, frame->height, frame->widthStep, QImage::Format_RGB888);
if (DoStart) emit
SendNewImage(Image);
AVFrame *pAVFrame=
avcodec_alloc_frame();
uint8_t *pBuffer=
(uint8_t*)malloc(avpicture_get_size(PIX_FMT_YUV420P, Width, Height)); {
avpicture_fill((AVPicture*)pAVFrame,
pBuffer, PIX_FMT_YUV420P, Width, Height);
IplImageToAVFrame(frame,
pAVFrame, Width, Height, PIX_FMT_YUV420P);
pAVFrame->pts= Frames;
int OutSize=
avcodec_encode_video(pCodecCtx, pOutBuffer, BYTEPIC, pAVFrame);
if (OutSize> 0) {
AVPacket Packet;
av_init_packet(&Packet);
//Packet.pts= Frames;
if (pCodecCtx-
>coded_frame->pts != AV_NOPTS_VALUE) {
Packet.pts=
av_rescale_q(pCodecCtx->coded_frame->pts, pCodecCtx->time_base, pVideoStream-
>time_base);
}
if (pCodecCtx-
>coded_frame->key_frame) Packet.flags |= AV_PKT_FLAG_KEY;
Packet.stream_index=
pVideoStream->index;
Packet.data=
pOutBuffer;
Packet.size= OutSize;
//qDebug() <<
"av_interleaved_write_frame before";
if
(av_interleaved_write_frame(pFormatCtx, &Packet)!= 0) qDebug() <<
"av_interleaved_write_frame Error!";
//qDebug() <<
"av_interleaved_write_frame after";
}
Frames++;
if (Frames> pCodecCtx-
>time_base.den / pCodecCtx->time_base.num * 10) break;
}{
av_free(pAVFrame);
free(pBuffer);
}
} else qDebug() <<
"QThCamera::run() frame= false";
}
qDebug() << Frames /
QDTStart.secsTo(QDateTime::currentDateTime());
}{
free(pOutBuffer);
}
if (av_write_trailer(pFormatCtx)!= 0)
qDebug() << "av_write_trailer Error!"; // Crash with H264!!!
//pFormatCtx->pb->opaque= NULL;
avio_close(pFormatCtx->pb);
}
QFMPGFileOut.close();
//} else qDebug() << "QFMPGFileOut.open() Error!";
avcodec_close(pVideoStream->codec);
}
}
for (int count= 0; (unsigned)count< pFormatCtx-
>nb_streams; count++) {
av_freep(&pFormatCtx->streams[count]->codec);
av_freep(&pFormatCtx->streams[count]);
}
}
av_free(pFormatCtx);
}
}
cvReleaseCapture(&Capture);
if (ExternalFrame) cvDestroyWindow("Frame");
}
qDebug() << "QThCamera::run() stop";
}
--
www.denisgottardello.it
Skype: mrdebug
Videosurveillance and home automation!
http://www.denisgottardello.it/DomusBoss/DomusBossIndice.php
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://ffmpeg.org/pipermail/libav-user/attachments/20110922/86602b63/attachment.html>
More information about the Libav-user
mailing list