Opened 9 years ago
Last modified 9 years ago
#4221 new defect
Teletext streams from DVB-S recording (mis)identified as MP3 audio with 0 channels / unknown stream
Reported by: | Oliver Freyermuth | Owned by: | |
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Priority: | normal | Component: | undetermined |
Version: | 2.5.2 | Keywords: | |
Cc: | Blocked By: | ||
Blocking: | Reproduced by developer: | no | |
Analyzed by developer: | no |
Description
When trying to decode a DVB-S recording with teletext streams in it, these streams are mistaken as e.g.
Stream #0:1[0x68], 127, 1/90000: Audio: mp3, 0 channels, s16p
Stream #0:5[0x69], 2, 1/90000: Unknown: none
This is with ffmpeg 2.5.2.
Full ffprobe-report created with
% ffprobe sample.ts -report
and sample.ts are attached.
Some more details about the streams:
Attachments (3)
Change History (8)
by , 9 years ago
Attachment: | ffprobe-20150104-044059.log added |
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comment:1 by , 9 years ago
I actually uploaded the sample.ts as teletext-streams-misrecognized.ts
to the ftp, adding a teletext-streams-misrecognized.txt
linking here. Much smaller files than the few MB sized one exhibit much less teletext data in comparison to video / audio.
by , 9 years ago
Attachment: | ffprobe-20150104-153725-sample2.log added |
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ffprobe for second sample (containing only teletext-pids)
comment:2 by , 9 years ago
I figured it would probably be more useful to only have the streams in question to have a larger sample of the interesting streams.
Patching mpv (which I use for recording) I did a recording of the same program, but only selecting the "0x68" and "0x69" streams.
The file is attached as sample2.ts, with corresponding full ffprobe report.
comment:4 by , 9 years ago
Thanks kierank for your quick reply!
This is indeed the case. I just checked with szap-s2 recording the same channel with PAT, PMT and teletext - ffprobe works fine then, while without PMT, the detection fails.
Still, without PMT, video and audio channels are detected just fine, only teletext gets broken.
I will try to implement PMT-PID extraction from PAT into mpv, this should fix it also there.
Does this invalidate the bug, as the issue can be resolved by adding the PMT (then you can just close it), or should it be left as a wish to have a clearer error message ("PMT missing => decoding may fail")?
Thanks again!
comment:5 by , 9 years ago
I already saw work on the git HEAD on this - I can confirm the subtitle-detection now appears to work even without PMT (I added the PMT to mpv by now, so it also works in a clean way). The teletext-detection does not, but that is not really too useful, anyways.
As PMT and PAT are now there in the TS, I encountered another somewhat related issue described in #4228.
ffprobe log