#7863 closed defect (fixed)
prompeg FEC problem
Reported by: | Thomas Edwards | Owned by: | |
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Priority: | normal | Component: | avformat |
Version: | git-master | Keywords: | prompeg |
Cc: | Blocked By: | ||
Blocking: | Reproduced by developer: | no | |
Analyzed by developer: | no |
Description
Summary of the bug:
rtp_mpegts with prompeg FEC has a problem, at least for L=5 D=20 - there are too many FEC packets, and some Column FEC payloads appear to be duplicates.
How to reproduce:
$ ffmpeg -f lavfi -i testsrc=duration=30:size=1280x720:rate=30 -f rtp_mpegts -fec prompeg=l=5:d=20 rtp://239.0.0.1:5000 ffmpeg version N-93595-gd7e8e62797 Copyright (c) 2000-2019 the FFmpeg developers built with gcc 7 (GCC) configuration: libavutil 56. 26.100 / 56. 26.100 libavcodec 58. 51.100 / 58. 51.100 libavformat 58. 27.102 / 58. 27.102 libavdevice 58. 7.100 / 58. 7.100 libavfilter 7. 48.100 / 7. 48.100 libswscale 5. 4.100 / 5. 4.100 libswresample 3. 4.100 / 3. 4.100
Capturing the output and using Wireshark Statistics/UDP Multicast Streams, you can see the output is:
UDP DST 5000 – PT=33 (MPEG TS): 2507 packets, avg. 3.121 Mbps
UDP DST 5001 – 2 (RTCP SR) packets, 223 kbps
UDP DST 5002 – PT=96, Column FEC, 622 packets, avg. 784 kbps
UDP DST 5004 – PT=96, Row FEC, 2507 packets, avg. 3.157 Mbps
If L=5 and D=20, there should be 25 FEC packets for every 100 source packets (5 Column FEC & 20 Row FEC packets). So for the 2507 source packets, there should be 125 Column FEC packets (but actually 622) and 500 Row FEC packets (but actually 2507).
I am also attaching Wireshark screenshots of example Column FEC packets with duplicated payloads and same SNBase low.
Attachments (2)
Change History (9)
by , 5 years ago
Attachment: | col_FEC_SN_2810.png added |
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comment:1 by , 5 years ago
Possibly related:
https://ffmpeg.org/pipermail/ffmpeg-devel/2019-March/241926.html
comment:2 by , 5 years ago
Component: | ffmpeg → avformat |
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Keywords: | fec removed |
Version: | 4.1 → git-master |
comment:3 by , 5 years ago
This square matrix FEC does appear to work OK however “prompeg=l=10:d=10”
comment:4 by , 4 years ago
Any reason didn't merge this patch (https://ffmpeg.org/pipermail/ffmpeg-devel/2019-March/241926.html)?
comment:6 by , 4 years ago
Resolution: | → fixed |
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Status: | new → closed |
merge the patch to fix this issue: https://ffmpeg.org/pipermail/ffmpeg-devel/2019-March/241926.html
Column FEC RTP SN 2810