record and play file using wrapper ffmpeg - ffmpeg

Question

I am using C# wrapper for ffmpeg from ffmpeg
I want record rtsp stream and play it but I can not decoder frame from file
using this code I write file test.avi
unsafe
{
AVFormatContext* context = FFmpegInvoke.avformat_alloc_context();
int video_stream_index=0;
FFmpegInvoke.av_register_all();
FFmpegInvoke.avcodec_register_all();
FFmpegInvoke.avformat_network_init();
//open rtsp
if (FFmpegInvoke.avformat_open_input(&context, "rtsp://admin:admin#192.168.0.71:554", null, null) != 0)
{
return ;
}
if (FFmpegInvoke.avformat_find_stream_info(context, null) < 0)
{
return ;
}
//search video stream
for (int i = 0; i < context->nb_streams; i++)
{
if (context->streams[i]->codec->codec_type == AVMediaType.AVMEDIA_TYPE_VIDEO)
video_stream_index = i;
}
AVPacket packet;
FFmpegInvoke.av_init_packet(&packet);
//open output file
AVOutputFormat* fmt = FFmpegInvoke.av_guess_format("h264", null, null);
AVFormatContext* oc = FFmpegInvoke.avformat_alloc_context();
oc->oformat = fmt;
FFmpegInvoke.avio_open2(&oc->pb, "test.mkv", FFmpegInvoke.AVIO_FLAG_WRITE, null, null);
AVStream* stream = null;
int cnt = 0;
//start reading packets from stream and write them to file
/// FFmpegInvoke.av_read_play(context);//play RTSP
while (FFmpegInvoke.av_read_frame(context, &packet) >= 0 && cnt < 1000)
{//read 100 frames
if (packet.stream_index == video_stream_index)
{//packet is video
if (stream == null)
{//create stream in file
stream = FFmpegInvoke.avformat_new_stream(oc, context->streams[video_stream_index]->codec->codec);
FFmpegInvoke.avcodec_copy_context(stream->codec, context->streams[video_stream_index]->codec);
stream->sample_aspect_ratio = context->streams[video_stream_index]->codec->sample_aspect_ratio;
FFmpegInvoke.avformat_write_header(oc, null);
}
packet.stream_index = stream->id;
var p1 = new FileInfo("test.mkv").Length;
FFmpegInvoke.av_write_frame(oc, &packet);
cnt++;
}
FFmpegInvoke.av_free_packet(&packet);
FFmpegInvoke.av_init_packet(&packet);
}
FFmpegInvoke.av_read_pause(context);
FFmpegInvoke.av_write_trailer(oc);
FFmpegInvoke.avio_close(oc->pb);
FFmpegInvoke.avformat_free_context(oc);
}
and using this code I want to play me file
unsafe{
string url = "test.mkv";
FFmpegInvoke.av_register_all();
FFmpegInvoke.avcodec_register_all();
FFmpegInvoke.avformat_network_init();
AVFormatContext* pFormatContext = FFmpegInvoke.avformat_alloc_context();
if (FFmpegInvoke.avformat_open_input(&pFormatContext, url, null, null) != 0)
throw new Exception("Could not open file");
if (FFmpegInvoke.avformat_find_stream_info(pFormatContext, null) != 0)
throw new Exception("Could not find stream info");
AVStream* pStream = null;
for (int i = 0; i < pFormatContext->nb_streams; i++)
{
if (pFormatContext->streams[i]->codec->codec_type == AVMediaType.AVMEDIA_TYPE_VIDEO)
{
pStream = pFormatContext->streams[i];
break;
}
}
var packet = new AVPacket();
AVPacket* pPacket = &packet;
FFmpegInvoke.av_init_packet(pPacket);
AVCodecContext codecContext = *(pStream->codec);
int width = codecContext.width;
int height = codecContext.height;
AVPixelFormat sourcePixFmt = codecContext.pix_fmt;
AVCodecID codecId = codecContext.codec_id;
var convertToPixFmt = AVPixelFormat.PIX_FMT_BGR24;
SwsContext* pConvertContext = FFmpegInvoke.sws_getContext(width, height, sourcePixFmt,
width, height, convertToPixFmt,
FFmpegInvoke.SWS_FAST_BILINEAR, null, null, null);
if (pConvertContext == null)
throw new Exception("Could not initialize the conversion context");
var pConvertedFrame = (AVPicture*)FFmpegInvoke.avcodec_alloc_frame();
int convertedFrameBufferSize = FFmpegInvoke.avpicture_get_size(convertToPixFmt, width, height);
var pConvertedFrameBuffer = (byte*)FFmpegInvoke.av_malloc((uint)convertedFrameBufferSize);
FFmpegInvoke.avpicture_fill(pConvertedFrame, pConvertedFrameBuffer, convertToPixFmt, width, height);
AVCodec* pCodec = FFmpegInvoke.avcodec_find_decoder(codecId);
if (pCodec == null)
throw new Exception("Unsupported codec");
// Reusing codec context from stream info,
// as an alternative way it could look like this: (but it works not for all kind of codecs)
// AVCodecContext* pCodecContext = FFmpegInvoke.avcodec_alloc_context3(pCodec);
AVCodecContext* pCodecContext = &codecContext;
if ((pCodec->capabilities & FFmpegInvoke.CODEC_CAP_TRUNCATED) == FFmpegInvoke.CODEC_CAP_TRUNCATED)
pCodecContext->flags |= FFmpegInvoke.CODEC_FLAG_TRUNCATED;
AVFrame* pDecodedFrame = FFmpegInvoke.avcodec_alloc_frame();
if (FFmpegInvoke.av_read_frame(pFormatContext, pPacket) < 0)
throw new System.IO.EndOfStreamException();
int gotPicture = 0;
int size = FFmpegInvoke.avcodec_decode_video2(pCodecContext, pDecodedFrame, &gotPicture, pPacket);
if (size < 0)
throw new Exception(string.Format("Error while decoding frame "));
if (gotPicture == 1)
{
}
size =-22.Why? what is wrong?How play my file using ffmpeg?