Reading Ogg stream causes increasing CPU usage

[Teodor Woźniak]

I am trying to record internet radio streaming in Ogg/Vorbis format.

FFmpeg uses more and more CPU. It may be related to:
Application provided invalid, non monotonically increasing dts to muxer in stream 0: 7072640 >= 7072640
showing in logs or metadata changing in the middle of stream, because it doesn't occur when feeding long Ogg/Vorbis stream from another instance of FFmpeg. The radio station uses Icecast.

How to reproduce:

wget http://lodz.radio.pionier.net.pl:8000/radiozak.ogg

leave it running for 30 minutes and press Ctrl-C. Do it between 22 and 16 o'clock UTC because otherwise there might be a long period without metadata change. (unfortunately you have to do it yourself, I can't publish recorded file because of copyrights. Or ask me and I'll put it on FTP, it's 48MB). Then:

cat radiozak.ogg | time ffmpeg -i - -map 0:a:0 -c:a copy -f null null

With n4.2.4 it returns:
1.28user 0.00system 0:01.28elapsed 99%CPU (0avgtext+0avgdata 7452maxresident)k

With n4.3:
59.54user 61.51system 2:01.06elapsed 99%CPU (0avgtext+0avgdata 135140maxresident)k

also note more memory usage.

It doesn't occur when the input is seekable:
ffmpeg -i radiozak.ogg -map 0:a:0 -c:a copy -f null null

It's regression since e983197cbc93420b67aa7e811be47d7278c2c8a2 (bisected).

Bisect helper script:

#!/bin/bash
set -e
cd "$(dirname "$0")"

./build_minimal || exit 255
cat radiozak.ogg | timeout 10 builddir/ffmpeg -i - -map 0:a:0 -c:a copy -f null null

build_minimal script is the same as in #8881

File open log as required by bug reporting instruction:

$ builddir/ffmpeg -v 9 -loglevel 99 -i radiozak.ogg
ffmpeg version N-98990-gf901d75bf1-minimal Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.3.0-10ubuntu2)
  configuration: --extra-version=minimal --enable-static --disable-doc --disable-swscale --disable-postproc --enable-gpl --disable-everything --enable-protocol=file --enable-protocol=pipe --enable-protocol=http --enable-muxer=ogg --enable-muxer=matroska --enable-muxer=webm --enable-muxer=segment --enable-muxer=null --enable-demuxer=ogg --enable-indev=lavfi --disable-hwaccels --enable-libvorbis --enable-filter=anoisesrc --enable-filter=amerge --enable-filter=aformat --enable-filter=aresample --enable-encoder=libvorbis --enable-decoder=pcm_f64le --enable-decoder=vorbis --enable-gnutls
  libavutil      56. 58.100 / 56. 58.100
  libavcodec     58.104.100 / 58.104.100
  libavformat    58. 53.100 / 58. 53.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswresample   3.  8.100 /  3.  8.100
Splitting the commandline.
Reading option '-v' ... matched as option 'v' (set logging level) with argument '9'.
Reading option '-loglevel' ... matched as option 'loglevel' (set logging level) with argument '99'.
Reading option '-i' ... matched as input url with argument 'radiozak.ogg'.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option v (set logging level) with argument 9.
Successfully parsed a group of options.
Parsing a group of options: input url radiozak.ogg.
Successfully parsed a group of options.
Opening an input file: radiozak.ogg.
[NULL @ 0x56477d5a65c0] Opening 'radiozak.ogg' for reading
[file @ 0x56477d5a7040] Setting default whitelist 'file,crypto,data'
Probing ogg score:100 size:2048
[ogg @ 0x56477d5a65c0] Format ogg probed with size=2048 and score=100
[ogg @ 0x56477d5a65c0] ogg_packet: curidx=-1
[ogg @ 0x56477d5a65c0] ogg_packet: idx=0 pstart=0 psize=0 segp=0 nsegs=1
[ogg @ 0x56477d5a65c0] ogg_packet: curidx=-1
[ogg @ 0x56477d5a65c0] ogg_packet: idx=0 pstart=30 psize=0 segp=0 nsegs=17
[ogg @ 0x56477d5a65c0] ogg_packet: curidx=0
[ogg @ 0x56477d5a65c0] ogg_packet: idx=0 pstart=437 psize=0 segp=2 nsegs=17
[ogg @ 0x56477d5a65c0] ogg_packet: curidx=-1
[ogg @ 0x56477d5a65c0] ogg_packet: idx=0 pstart=4120 psize=0 segp=0 nsegs=25
[ogg @ 0x56477d5a65c0] found headers
[ogg @ 0x56477d5a65c0] failed to create or replace stream
[ogg @ 0x56477d5a65c0] Before avformat_find_stream_info() pos: 8412 bytes read:65536 seeks:4 nb_streams:1
[ogg @ 0x56477d5a65c0] ogg_packet: curidx=0
[ogg @ 0x56477d5a65c0] ogg_packet: idx=0 pstart=4120 psize=0 segp=0 nsegs=25
[ogg @ 0x56477d5a65c0] All info found
[ogg @ 0x56477d5a65c0] Estimating duration from bitrate, this may be inaccurate
[ogg @ 0x56477d5a65c0] stream 0: start_time: 139.541 duration: 1769.19
[ogg @ 0x56477d5a65c0] format: start_time: 139.541 duration: 1769.19 (estimate from bit rate) bitrate=224 kb/s
[ogg @ 0x56477d5a65c0] After avformat_find_stream_info() pos: 8412 bytes read:65536 seeks:4 frames:1
Input #0, ogg, from 'radiozak.ogg':
  Duration: 00:29:29.19, start: 139.541333, bitrate: 224 kb/s
    Stream #0:0, 1, 1/48000: Audio: vorbis, 48000 Hz, stereo, fltp, 224 kb/s
    Metadata:
      ARTIST          : Pro8l3m
      TITLE           : Art.258  [ŻAK - STUDENCKIE RADIO POLITECHNIKI ŁÓDZKIEJ  88,8 MHz  www.zak.lodz.pl]
      GENRE           : Alternative
      CONTACT         : http://www.zak.lodz.pl/
      comment         : ŻAK 88,8 MHz - studenckie radio Politechniki Łódzkiej
      LOCATION        : III DS PŁ, al. Politechniki 7, 93-590 Łódź, Polska
      ORGANIZATION    : Politechnika Łódzka
Successfully opened the file.
At least one output file must be specified
[AVIOContext @ 0x56477d5af400] Statistics: 65536 bytes read, 4 seeks

[Carl Eugen Hoyos]

Duplicate of ticket #8778