[FFmpeg-user] H264 encoder: Bad video output.

slim tabka tabkaslim at gmail.com
Mon Apr 11 12:27:14 CEST 2016


Hi every one,
I'm streaming a live channel but after a random amount of time, the video
become scrambled (Unviewable output, there's a sample in this link
refs3.ts: https://www.dropbox.com/s/99te0h2fldz8s9f/refs3.ts?dl=0).
The input is channel 4 HD from Astra 2G (28.2°E) (the issue is only with
some HD channels) I'm using mumudvb to send the stream to ffmpeg.
The problem is that when the video become scrambled when I check the source
(direct stream from mumudvb) the stream works fine.


This the part of the log that I always get multiple times each second (see
refs.log for full log:
https://www.dropbox.com/s/y2qzllu7t1s98cb/ref3.log?dl=0) I reduced the size
of the file but it the same log repeating it self over and over again:

"[h264 @ 0x23834e0] top block unavailable for requested intra4x4 mode -1 at
28 0
[h264 @ 0x23834e0] error while decoding MB 28 0, bytestream 11966
[h264 @ 0x2389040] Reference 2 >= 2
[h264 @ 0x2389040] error while decoding MB 42 1, bytestream 11664
[h264 @ 0x28b5ec0] Reference 2 >= 2
[h264 @ 0x28b5ec0] error while decoding MB 37 0, bytestream 12177
[h264 @ 0x29023c0] Reference 2 >= 2
[h264 @ 0x29023c0] error while decoding MB 27 1, bytestream 12123
[h264 @ 0x2914e00] top block unavailable for requested intra4x4 mode -1 at
10 0
[h264 @ 0x2914e00] error while decoding MB 10 0, bytestream 46924
[h264 @ 0x2a94280] Reference 5 >= 2
[h264 @ 0x2a94280] error while decoding MB 3 1, bytestream 12935
[h264 @ 0x2497260] Reference 2 >= 2
[h264 @ 0x2497260] error while decoding MB 41 1, bytestream 10533
[h264 @ 0x2483740] Reference 2 >= 2
[h264 @ 0x2483740] error while decoding MB 27 0, bytestream 9397
[h264 @ 0x23834e0] Reference 2 >= 2
[h264 @ 0x23834e0] error while decoding MB 20 1, bytestream 9425
[h264 @ 0x2389040] Reference 2 >= 2
[h264 @ 0x2389040] error while decoding MB 53 0, bytestream 7093
[h264 @ 0x28b5ec0] Reference 2 >= 2
[h264 @ 0x28b5ec0] error while decoding MB 50 1, bytestream 8663
[h264 @ 0x29023c0] Reference 4 >= 4
"

This is the full command I'm using :
ffmpeg -reconnect 1 -reconnect_at_eof 1 -reconnect_streamed 1
-reconnect_delay_max 2 -i {input} -c:a aac -ar 48000 -b:a 128k -sn -s
1280x720 -r 25 -c:v libx264 -b:v 2000k -profile:v baseline -level 3.1 -vf
yadif -maxrate 2100 -minrate 2100 -bufsize 500 -flags +loop -deblock 0:0
-cmp +chroma -coder 0 -me_range 16 -keyint_min 2 -g 5 -refs 3 -sc_threshold
40 -mixed-refs 1 -8x8dct 1 -i_qfactor 0.71 -rc_eq 'blurCplx^(1-qComp)'
-qcomp 0.6 -qmin 5 -qmax 51 -qdiff 4 -hls_time 5 -hls_list_size 5
-start_number 1 -hls_flags delete_segments {output}.m3u8

>From the log I suspected a problem with the refrence frames when I reduce
it to 0 the problem appears directly with 3 the problem appears after few
hours. I'm not sure that this is the problem, I made several modification
on the h264 parameters but still no luck.
In this link they have almost the same issue (
https://github.com/raspberrypi/firmware/issues/255 )

They said :

> "The broken MMCO commands keep the old frame in the DPB until the
> stream's frame_num values wrap around and come back to the old one, at
> which point it ends up getting used as a reference.
> This is forbidden in the h264 standard, but we aren't detecting invalid
> streams doing this. CL451051 has a shelved change that seems to fix this on
> a DK, but I need to make sure it hasn't broken other things.
> (later) It passed the hwcodec_test testset"

Could it be the same issue for ffmpeg, because some time when you can see
some part of the video you can see that the 2 last frames are repeated over
and over.

I'm out of option can anyone point me to the right direction. Thank you for
you time.

Best Regards Slim TABKA.


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