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using ASIO to implement interrupt_callback for ffmpeg
22 décembre 2020, par Sergey KolesnikI am trying to properly implement an
interrupt_callbackusing ASIO timer foravformat_open_input,av_read_frameand possibly for other functions. I can't get it to work when receiving a udp video stream.

I've written a class that waits for periods of time using ASIO timer. Its constructor takes an
io_contextfrom the thread ofavformat_open_inputexecution and an overall timeout period to wait for. By default it waits for 20 ms each time, but can be set to wait longer periods.

class InterruptCallback
{
public:

 constexpr static std::chrono::milliseconds basic_period()
 {
 return std::chrono::milliseconds(20);
 }

 explicit InterruptCallback(asio::io_context &asioContext,
 std::chrono::milliseconds timeout,
 std::chrono::milliseconds period =
 basic_period())
 : waitingPeriod_(period),
 attempts_(timeout / waitingPeriod_),
 timer_(asioContext)
 {
 attempts_ = attempts_ ? attempts_ : 1;
 }

 int wait()
 {
 timer_.expires_after(waitingPeriod_);
 timer_.wait();
 return int(!--attempts_);
 }

 static int wait(void *opaqueCallback)
 {
 auto callback = reinterpret_cast<interruptcallback>(opaqueCallback);
 return callback->wait();
 }

private:
 std::chrono::milliseconds waitingPeriod_;
 size_t attempts_;

 asio::steady_timer timer_;
};
</interruptcallback>

This approach works when no udp stream is being received. Also it returns relatively fast when a udp is being received.


However, when I set a
AVFormatContext::interrupt_callbackI get a lot of errors on decoding.
avformat_find_stream_infocan return fast enough, butAVCodecContextwill be invalid.
Or it can take a very long time to execute.

asio::io_context mainThreadContext{};

 AVFormatContext *pFormatContext = avformat_alloc_context();

 {
 InterruptCallback interruptCallback{mainThreadContext,
 std::chrono::milliseconds(2000)
 };

 pFormatContext->interrupt_callback.callback = &InterruptCallback::wait;
 pFormatContext->interrupt_callback.opaque = &interruptCallback;

 const auto resOpen = avformat_open_input(&pFormatContext,
 containerAddress.c_str(),
 nullptr,
 nullptr);
 if (resOpen < 0)
 {
 std::cerr << "Failed to open stream from: " << containerAddress << std::endl;
 return -1;
 }
 }
 auto avFormatExit = sg::make_scope_exit(
 [&pFormatContext]
 {
 avformat_close_input(&pFormatContext);
 });

 pFormatContext->flags = AVFMT_FLAG_NOBUFFER | AVFMT_FLAG_FLUSH_PACKETS;

 int error = avformat_find_stream_info(pFormatContext, nullptr);


It can happen on the line where I query the stream info, but is also frequent for decoding loop.
These are some of the possible errors :


[h264 @ 00000000027f4000] non-existing PPS 0 referenced
[h264 @ 00000000027f4000] non-existing PPS 0 referenced
[h264 @ 00000000027f4000] decode_slice_header error
[h264 @ 00000000027f4000] no frame!
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000027f4000] concealing 7217 DC, 7217 AC, 7217 MV errors in I frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000027f4000] concealing 7588 DC, 7588 AC, 7588 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000027f4000] error while decoding MB 83 5, bytestream -6
[h264 @ 00000000027f4000] concealing 7526 DC, 7526 AC, 7526 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000027f4000] concealing 7072 DC, 7072 AC, 7072 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000027f4000] concealing 7651 DC, 7651 AC, 7651 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000027f4000] concealing 5806 DC, 5806 AC, 5806 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000027f4000] left block unavailable for requested intra mode
[h264 @ 00000000027f4000] error while decoding MB 0 5, bytestream 8107
[h264 @ 00000000027f4000] concealing 7609 DC, 7609 AC, 7609 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 6669 DC, 6669 AC, 6669 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7254 DC, 7254 AC, 7254 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7048 DC, 7048 AC, 7048 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7061 DC, 7061 AC, 7061 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7220 DC, 7220 AC, 7220 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 5722 DC, 5722 AC, 5722 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7230 DC, 7230 AC, 7230 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7085 DC, 7085 AC, 7085 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7745 DC, 7745 AC, 7745 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 6907 DC, 6907 AC, 6907 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7301 DC, 7301 AC, 7301 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 5664 DC, 5664 AC, 5664 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] error while decoding MB 105 8, bytestream -8
[h264 @ 00000000051a0040] concealing 7144 DC, 7144 AC, 7144 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7487 DC, 7487 AC, 7487 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 6912 DC, 6912 AC, 6912 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] error while decoding MB 39 8, bytestream -6
[h264 @ 00000000051a0040] concealing 7210 DC, 7210 AC, 7210 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 5262 DC, 5262 AC, 5262 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] error while decoding MB 54 8, bytestream -5
[h264 @ 00000000051a0040] concealing 7195 DC, 7195 AC, 7195 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7298 DC, 7298 AC, 7298 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 6819 DC, 6819 AC, 6819 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 5692 DC, 5692 AC, 5692 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 6684 DC, 6684 AC, 6684 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7600 DC, 7600 AC, 7600 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 6123 DC, 6123 AC, 6123 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7689 DC, 7689 AC, 7689 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 6846 DC, 6846 AC, 6846 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] left block unavailable for requested intra4x4 mode -1
[h264 @ 00000000051a0040] error while decoding MB 0 10, bytestream 1892
[h264 @ 00000000051a0040] concealing 7009 DC, 7009 AC, 7009 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 5288 DC, 5288 AC, 5288 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7932 DC, 7932 AC, 7932 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 7039 DC, 7039 AC, 7039 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] error while decoding MB 105 11, bytestream -5
[h264 @ 00000000051a0040] concealing 6784 DC, 6784 AC, 6784 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 6918 DC, 6918 AC, 6918 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] concealing 6483 DC, 6483 AC, 6483 MV errors in P frame
[h264 @ 00000000051a0040] error while decoding MB 118 1, bytestream -10
[h264 @ 00000000051a0040] concealing 7971 DC, 7971 AC, 7971 MV errors in P frame
[mpegts @ 00000000027dea40] PES packet size mismatch
[h264 @ 00000000051a0040] QP 4294967266 out of range
[h264 @ 00000000051a0040] decode_slice_header error
[h264 @ 00000000051a0040] no frame!
Error sending packet for decoding

Process finished with exit code 1


When I don't set an
interrupt_callback, no errors occur, stream info is found very quickly.

So, the questions are :


- 

- What am I doing wrong when implementing the interrupt callback ?
- Why don't I get an error when I receive an invalid codec context from
avformat_find_stream_info?






-
ffmpeg : don't delay printing initial stats
21 décembre 2020, par Gyan Doshi -
Skipping Sequential n Frames Every Selected Time or Frames with FFmpeg [closed]
23 décembre 2020, par ihyyaAHow can i stream video by skipping Specific number of Sequential frames or time every selected number of frames or time.
I searched a lot and could not find the code I was looking for.


I tried codes like this :


ffmpeg.exe -re -i "link.m3u8"-vf select="not(mod(n\, 200))" -acodec aac -c:v libx264 -preset veryfast -strict experimental -f flv "rtmp://.."


But the output is one frame every specific frames or time, but i want selected number of Sequential frames every selected period of time or frames.


I think this Question is not Duplicate


Thanks.


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