[Libav-user] Separating decoding and processing frames into threads

[Nikita Vaňků]

I appreciate your interest!

> Hardware frames often resize in the memory of the device or its driver.
> Therefore, only a limited number of them can exist at a time. It seems
> your queue is too large for that.

I have tried to resize the queue to an absolute minimum, yet the
problem persisted in various OS and devices.

> You probably need to copy the frame at least once.

I do not understand what exactly you mean

I ran the SW decoder for several hours and noticed no memory leak.

Out of frustration, I tried to minimize the code, I now know that if I
keep reusing a single frame (allocate it once and never free it) the
problem disappears. But as soon as I try to allocate new frames for
each decoded frame while using HW acceleration I start running into
these issues.

The code for this is very simple on the decoding side I simply:

            AVFrame* frame = av_frame_alloc();
            ret = avcodec_receive_frame(m_codecContext, frame);
            av_packet_unref(m_packet);
            if (ret == AVERROR(EAGAIN)) {
                av_frame_free(&frame);
                continue;
            } else if (ret == AVERROR_EOF) {
                av_frame_free(&frame);
                break;
            } else if (ret != 0) {
                av_frame_free(&frame);
                break;
            }

I skipped the processing and just call av_frame_free on the processing
side. The queue for this purpose is a size of 4. Errors in linux
differs from those experienced on Windows

[h264 @ 0x7f93f00de580] get_buffer() failed
[h264 @ 0x7f93f00de580] decode_slice_header error
[h264 @ 0x7f93f00de580] no frame!

Also I forgot to mention I'm using FFMpeg 5.1.3.

Regards,
Nikita