[FFmpeg-user] Relevant image degradation after 6-8 hour of encoding

[Massimo Battistel]

Hello,
I'm trying to transcode a live stream and I faced the issue in object.
Picture looks much more "pixellated" especially on I-frames, giving the
video a "pulsing" effect.
I've attached a screenshot of image quality after ~1h and after ~8h.

My test stream was a single video in loop.

This is the command line I used:

ffmpeg -probesize 20M -channel_layout stereo -i <any_stream> -vcodec
mpeg2video -pix_fmt yuv420p  -aspect 16:9 -b:v 1200k -minrate 1200k
-maxrate 1200k -trellis 2 -g 24 -bf 2 -acodec mp2 -ac 2 -ar 48000 -b:a 128k
 -streamid 0:70 -streamid 1:71  -f mpegts -flush_packets 0 udp://
127.0.0.1:1500?pkt_size=1316

ffmpeg version N-66232-g5e3da25 Copyright (c) 2000-2014 the FFmpeg
developers
  built on Sep 10 2014 22:06:30 with gcc 4.8.3 (GCC)
  configuration: --disable-static --enable-shared --enable-gpl
--enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib
--enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv
--enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca
--enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc
--enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb
--enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus
--enable-librtmp --enable-libschroedinger --enable-libsoxr
--enable-libspeex --enable-libtheora --enable-libtwolame
--enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc
--enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp
--enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid
--enable-decklink --enable-zlib
  libavutil      54.  7.100 / 54.  7.100
  libavcodec     56.  1.100 / 56.  1.100
  libavformat    56.  4.101 / 56.  4.101
  libavdevice    56.  0.100 / 56.  0.100
  libavfilter     5.  1.100 /  5.  1.100
  libswscale      3.  0.100 /  3.  0.100
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  0.100 / 53.  0.100
[h264 @ 02660fc0] non-existing PPS 0 referenced
    Last message repeated 1 times
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] no frame!
[h264 @ 02660fc0] non-existing PPS 0 referenced
    Last message repeated 1 times
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] non-existing PPS 0 referenced
[h264 @ 02660fc0] decode_slice_header error
[h264 @ 02660fc0] no frame!
Input #0, mpegts, from 'udp://127.0.0.1:1400':
  Duration: N/A, start: 152.956000, bitrate: 122 kb/s
  Program 1
    Metadata:
      service_name    : Service01
      service_provider: FFmpeg
    Stream #0:0[0x100]: Video: h264 (Main) ([27][0][0][0] / 0x001B),
yuv420p, 720x576 [SAR 64:45 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x101]: Audio: aac ([15][0][0][0] / 0x000F), 48000 Hz,
stereo, fltp, 122 kb/s
[mpeg2video @ 049f0740] Automatically choosing VBV buffer size of 224 kbyte
[mpeg2video @ 049f0740] Warning vbv_delay will be set to 0xFFFF (=VBR) as
the specified vbv buffer is too large for the given bitrate!
Output #0, mpegts, to 'udp://127.0.0.1:1500?pkt_size=1316':
  Metadata:
    encoder         : Lavf56.4.101
    Stream #0:0: Video: mpeg2video, yuv420p, 720x576 [SAR 64:45 DAR 16:9],
q=2-31, 1200 kb/s, 25 fps, 90k tbn, 25 tbc
    Metadata:
      encoder         : Lavc56.1.100 mpeg2video
    Stream #0:1: Audio: mp2, 48000 Hz, stereo, s16, 128 kb/s
    Metadata:
      encoder         : Lavc56.1.100 mp2
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> mpeg2video (native))
  Stream #0:1 -> #0:1 (aac (native) -> mp2 (native))
Press [q] to stop, [?] for help


I would like to know which encoding parameters change over time and how to
control them (if possible.)


thanks,
MB
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