Screen Recording with FFmpeg-Lib with c++ - c++

Question

I'm trying to record the whole desktop stream with FFmpeg on Windows.
I found a working example here. The Problem is that some og the functions depricated. So I tried to replace them with the updated ones.
But there are some slight problems. The error "has triggered a breakpoint." occurse and also "not able to read the location."
The bigger problem is that I don't know if this is the right way to do this..
My code looks like this:
using namespace std;
/* initialize the resources*/
Recorder::Recorder()
{
av_register_all();
avcodec_register_all();
avdevice_register_all();
cout<<"\nall required functions are registered successfully";
}
/* uninitialize the resources */
Recorder::~Recorder()
{
avformat_close_input(&pAVFormatContext);
if( !pAVFormatContext )
{
cout<<"\nfile closed sucessfully";
}
else
{
cout<<"\nunable to close the file";
exit(1);
}
avformat_free_context(pAVFormatContext);
if( !pAVFormatContext )
{
cout<<"\navformat free successfully";
}
else
{
cout<<"\nunable to free avformat context";
exit(1);
}
}
/* establishing the connection between camera or screen through its respective folder */
int Recorder::openCamera()
{
value = 0;
options = NULL;
pAVFormatContext = NULL;
pAVFormatContext = avformat_alloc_context();//Allocate an AVFormatContext.
openScreen(pAVFormatContext);
/* set frame per second */
value = av_dict_set( &options,"framerate","30",0 );
if(value < 0)
{
cout<<"\nerror in setting dictionary value";
exit(1);
}
value = av_dict_set( &options, "preset", "medium", 0 );
if(value < 0)
{
cout<<"\nerror in setting preset values";
exit(1);
}
// value = avformat_find_stream_info(pAVFormatContext,NULL);
if(value < 0)
{
cout<<"\nunable to find the stream information";
exit(1);
}
VideoStreamIndx = -1;
/* find the first video stream index . Also there is an API available to do the below operations */
for(int i = 0; i < pAVFormatContext->nb_streams; i++ ) // find video stream posistion/index.
{
if( pAVFormatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO )
{
VideoStreamIndx = i;
break;
}
}
if( VideoStreamIndx == -1)
{
cout<<"\nunable to find the video stream index. (-1)";
exit(1);
}
// assign pAVFormatContext to VideoStreamIndx
pAVCodecContext = pAVFormatContext->streams[VideoStreamIndx]->codec;
pAVCodec = avcodec_find_decoder(pAVCodecContext->codec_id);
if( pAVCodec == NULL )
{
cout<<"\nunable to find the decoder";
exit(1);
}
value = avcodec_open2(pAVCodecContext , pAVCodec , NULL);//Initialize the AVCodecContext to use the given AVCodec.
if( value < 0 )
{
cout<<"\nunable to open the av codec";
exit(1);
}
}
/* initialize the video output file and its properties */
int Recorder::init_outputfile()
{
outAVFormatContext = NULL;
value = 0;
output_file = "output.mp4";
avformat_alloc_output_context2(&outAVFormatContext, NULL, NULL, output_file);
if (!outAVFormatContext)
{
cout<<"\nerror in allocating av format output context";
exit(1);
}
/* Returns the output format in the list of registered output formats which best matches the provided parameters, or returns NULL if there is no match. */
output_format = av_guess_format(NULL, output_file ,NULL);
if( !output_format )
{
cout<<"\nerror in guessing the video format. try with correct format";
exit(1);
}
video_st = avformat_new_stream(outAVFormatContext ,NULL);
if( !video_st )
{
cout<<"\nerror in creating a av format new stream";
exit(1);
}
if (codec_id == AV_CODEC_ID_H264)
{
av_opt_set(outAVCodecContext->priv_data, "preset", "slow", 0);
}
outAVCodec = avcodec_find_encoder(AV_CODEC_ID_MPEG4);
if (!outAVCodec)
{
cout << "\nerror in finding the av codecs. try again with correct codec";
exit(1);
}
outAVCodecContext = avcodec_alloc_context3(outAVCodec);
if( !outAVCodecContext )
{
cout<<"\nerror in allocating the codec contexts";
exit(1);
}
/* set property of the video file */
outAVCodecContext = video_st->codec;
outAVCodecContext->codec_id = AV_CODEC_ID_MPEG4;// AV_CODEC_ID_MPEG4; // AV_CODEC_ID_H264 // AV_CODEC_ID_MPEG1VIDEO
outAVCodecContext->codec_type = AVMEDIA_TYPE_VIDEO;
outAVCodecContext->pix_fmt = AV_PIX_FMT_YUV420P;
outAVCodecContext->bit_rate = 400000; // 2500000
outAVCodecContext->width = 1920;
outAVCodecContext->height = 1080;
outAVCodecContext->gop_size = 3;
outAVCodecContext->max_b_frames = 2;
outAVCodecContext->time_base.num = 1;
outAVCodecContext->time_base.den = 30; //15fps
/* Some container formats (like MP4) require global headers to be present
Mark the encoder so that it behaves accordingly. */
if ( outAVFormatContext->oformat->flags & AVFMT_GLOBALHEADER)
{
outAVCodecContext->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
}
value = avcodec_open2(outAVCodecContext, outAVCodec, NULL);
if( value < 0)
{
cout<<"\nerror in opening the avcodec";
exit(1);
}
/* create empty video file */
if ( !(outAVFormatContext->flags & AVFMT_NOFILE) )
{
if( avio_open2(&outAVFormatContext->pb , output_file , AVIO_FLAG_WRITE ,NULL, NULL) < 0 )
{
cout<<"\nerror in creating the video file";
exit(1);
}
}
if(!outAVFormatContext->nb_streams)
{
cout<<"\noutput file dose not contain any stream";
exit(1);
}
/* imp: mp4 container or some advanced container file required header information*/
value = avformat_write_header(outAVFormatContext , &options);
if(value < 0)
{
cout<<"\nerror in writing the header context";
exit(1);
}
/*
// uncomment here to view the complete video file informations
cout<<"\n\nOutput file information :\n\n";
av_dump_format(outAVFormatContext , 0 ,output_file ,1);
*/
}
int Recorder::stop() {
threading = false;
demux->join();
rescale->join();
mux->join();
return 0;
}
int Recorder::start() {
initVideoThreads();
return 0;
}
int Recorder::initVideoThreads() {
demux = new thread(&Recorder::demuxVideoStream, this, pAVCodecContext, pAVFormatContext, VideoStreamIndx);
rescale = new thread(&Recorder::rescaleVideoStream, this, pAVCodecContext, outAVCodecContext);
demux = new thread(&Recorder::encodeVideoStream, this, outAVCodecContext);
return 0;
}
void Recorder::demuxVideoStream(AVCodecContext* codecContext, AVFormatContext* formatContext, int streamIndex)
{
// init packet
AVPacket* packet = (AVPacket*)av_malloc(sizeof(AVPacket));
av_init_packet(packet);
int ctr = 0;
while (threading)
{
if (av_read_frame(formatContext, packet) < 0) {
exit(1);
}
if (packet->stream_index == streamIndex)
{
int return_value; // = 0;
ctr++;
do
{
return_value = avcodec_send_packet(codecContext, packet);
} while (return_value == AVERROR(EAGAIN) && threading);
//int i = avcodec_send_packet(codecContext, packet);
if (return_value < 0 && threading) { // call Decoder
cout << "unable to decode video";
exit(1);
}
}
}
avcodec_send_packet(codecContext, NULL); // flush decoder
// return 0;
}
void Recorder::rescaleVideoStream(AVCodecContext* inCodecContext, AVCodecContext* outCodecContext)
{
bool closing = false;
AVFrame* inFrame = av_frame_alloc();
if (!inFrame)
{
cout << "\nunable to release the avframe resources";
exit(1);
}
int nbytes = av_image_get_buffer_size(outAVCodecContext->pix_fmt, outAVCodecContext->width, outAVCodecContext->height, 32);
uint8_t* video_outbuf = (uint8_t*)av_malloc(nbytes);
if (video_outbuf == NULL)
{
cout << "\nunable to allocate memory";
exit(1);
}
AVFrame* outFrame = av_frame_alloc();//Allocate an AVFrame and set its fields to default values.
if (!outFrame)
{
cout << "\nunable to release the avframe resources for outframe";
exit(1);
}
// Setup the data pointers and linesizes based on the specified image parameters and the provided array.
int value = av_image_fill_arrays(outFrame->data, outFrame->linesize, video_outbuf, AV_PIX_FMT_YUV420P, outAVCodecContext->width, outAVCodecContext->height, 1); // returns : the size in bytes required for src
if (value < 0)
{
cout << "\nerror in filling image array";
}
int ctr = 0;
while (threading || !closing) {
int value = avcodec_receive_frame(inCodecContext, inFrame);
if (value == 0) {
ctr++;
SwsContext* swsCtx_ = sws_getContext(inCodecContext->width,
inCodecContext->height,
inCodecContext->pix_fmt,
outAVCodecContext->width,
outAVCodecContext->height,
outAVCodecContext->pix_fmt,
SWS_BICUBIC, NULL, NULL, NULL);
sws_scale(swsCtx_, inFrame->data, inFrame->linesize, 0, inCodecContext->height, outFrame->data, outFrame->linesize);
int return_value;
do
{
return_value = avcodec_send_frame(outCodecContext, outFrame);
} while (return_value == AVERROR(EAGAIN) && threading);
}
closing = (value == AVERROR_EOF);
}
avcodec_send_frame(outCodecContext, NULL);
// av_free(video_outbuf);
// return 0;
}
void Recorder::encodeVideoStream(AVCodecContext* codecContext)
{
bool closing = true;
AVPacket* packet = (AVPacket*)av_malloc(sizeof(AVPacket));
av_init_packet(packet);
int ctr = 0;
while (threading || !closing) {
packet->data = NULL; // packet data will be allocated by the encoder
packet->size = 0;
ctr++;
int value = avcodec_receive_packet(codecContext, packet);
if (value == 0) {
if (packet->pts != AV_NOPTS_VALUE)
packet->pts = av_rescale_q(packet->pts, video_st->codec->time_base, video_st->time_base);
if (packet->dts != AV_NOPTS_VALUE)
packet->dts = av_rescale_q(packet->dts, video_st->codec->time_base, video_st->time_base);
//printf("Write frame %3d (size= %2d)\n", j++, packet->size / 1000);
if (av_write_frame(outAVFormatContext, packet) != 0)
{
cout << "\nerror in writing video frame";
}
}
closing = (value == AVERROR_EOF);
}
value = av_write_trailer(outAVFormatContext);
if (value < 0)
{
cout << "\nerror in writing av trailer";
exit(1);
}
// av_free(packet);
// return 0;
}
int Recorder::openScreen(AVFormatContext* pFormatCtx) {
/*
X11 video input device.
To enable this input device during configuration you need libxcb installed on your system. It will be automatically detected during configuration.
This device allows one to capture a region of an X11 display.
refer : https://www.ffmpeg.org/ffmpeg-devices.html#x11grab
*/
/* current below is for screen recording. to connect with camera use v4l2 as a input parameter for av_find_input_format */
pAVInputFormat = av_find_input_format("gdigrab");
//value = avformat_open_input(&pAVFormatContext, ":0.0+10,250", pAVInputFormat, NULL);
value = avformat_open_input(&pAVFormatContext, "desktop", pAVInputFormat, NULL);
if (value != 0)
{
cout << "\nerror in opening input device";
exit(1);
}
return 0;
}