Hi,
I'm getting corrupted frames at the very beginning of the video when decoding
HEVC streamed via FramedSource and H265VideoRTPSink.
For testing and trying to isolate the issue, I write the raw coded and
to-be-sent data to disk in my server code, and play it back, using my own
decoder code, ffplay, MPC, and VLC. When I do this, there is no problem, at
least none visible, also none of the players reports any errors.
As a next step, I write the raw to-be-decoded data, as received via RTP
streaming, to disk from within my client code. When I play this back, there
seems to be data missing or broken. ffplay gives the following output:
Input #0, hevc, from 'test.mp4':0B f=0/0
Duration: N/A, bitrate: N/A
Stream #0:0: Video: hevc (Main), yuv420p(tv), 6176x2076 [SAR 1:1 DAR
1544:519], 30 fps, 30 tbr, 1200k tbn, 30 tbc
[hevc @ 0000000002ee2f60] Could not find ref with POC 1 0B f=0/0
nan M-V: nan fd= 0 aq= 0KB vq= 132KB sq= 0B f=0/0
This happens quite frequently, but not always. Server and client are running on
the same machine for starters, so there is no network to blame. The video I am
sending is quite large in terms of frame dimensions (6176x2076), so I turned
the OutPacketBuffer::maxSize up to 500k, but it also happens with 3088x2076,
although not as often. I googled a bit and the error "Could not find ref with
POC 1" seems to hint to a demuxing problem?
In order to eliminate sources of error, I tried to reproduce this with as
little of my own code as possible. For that I write a file with 6176x2076 HEVC
encoded data to disk and doublecheck with ffplay -- the file seems to be fine.
I use live555MediaServer.exe as an RTSP server and VLC as a client -> the video
displayed by VLC is broken. I also tried to capture the received data and write
it to disk via openRTSP. The produced file is also broken, as I can see when I
play it back with ffplay, although there is no error reported in this case. MPC
also shows broken frames, VLC refuses to render the file at all.
So I guess, what I'm asking is:
1) First, and most importantly: does anybody have an idea where this issue may
be coming from and what I can do about it? Or how I could figure out what the
actual issue is?
2) What is the best way to doublecheck in my code if the received data is
indeed valid? I tried to compare the sizes of NAL packages fed in my overloaded
version of FramedSource::deliverFrame vs. the package sizes I get in
MediaSink::afterReading, but I cannot see any relation -- maybe this could tell
something, but I'm not sure, I think I would have to become an expert in HEVC
payloading first, which I'm not at this point.
3) Is there anything particular I have to do with the received data, I'm not
aware of? From the MPlayer source code I got the impression, I just have to
prefix the data with 0x000001 and then feed it to the decoder, which I do in my
overloaded MediaSink::afterReading, but maybe I overlooked something. Anyways,
this doesn't seem to be solving the issue at hand, since I can reproduce the
error without using my own code at all.
Thanks,
Roland
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