Opened 12 years ago

Closed 10 years ago

#5016 closed defect (invalid)

AVFormat Decoder attempts to play zero bitrate video streams

Reported by: dluzin@… Owned by: Janne Grunau
Priority: minor Milestone: unknown
Component: MythTV - Video Playback Version: 0.21-fixes
Severity: medium Keywords: DVB-S MPEG2 playing problem
Cc: Ticket locked: no

Description

Hi!

I've installed MythTV few days ago and get the following trouble: Some of free (not encrypted) DVB-S channels can't be played my mythfrontend. Same time if I record some video by mythbackend the output file may be played by MPlayer or Windows media player, but mythfrontend can't play these files. I've tried MythTV release-0.21-fixes, trunk (16745) - same result. I'm attaching two log files and posting two .mpg samples to rapidshare (files' sizes are 20MB and 27MB).

Samples:

http://rapidshare.com/files/101416870/2900_20080322131400.mpg http://rapidshare.com/files/101419702/7700_20080322131500.mpg

Attachments (4)

1.txt (2.1 KB) - added by dluzin@… 12 years ago.
mythfrontend log
2.txt (4.6 KB) - added by dluzin@… 12 years ago.
mythfrontend log
avformatdecoder.diff (916 bytes) - added by dluzin@… 12 years ago.
Temporary fix
avformatdecoder.2.diff (925 bytes) - added by dluzin@… 12 years ago.
This one should be readable

Download all attachments as: .zip

Change History (16)

Changed 12 years ago by dluzin@…

Attachment: 1.txt added

mythfrontend log

Changed 12 years ago by dluzin@…

Attachment: 2.txt added

mythfrontend log

comment:1 Changed 12 years ago by dluzin@…

Tried to transcode these files by ffmpeg with -vcodec copy and -acodec copy options to leave video and audio streams unchanged, then transcoded file can be normally played my mythfrontend's internal player.

So it looks like demuxer problem of internal player.

comment:2 Changed 12 years ago by dluzin@…

There is some problems with stream type detection. as MPlayer shows attached files contetns three streams: stream 0 - type 0xffffffff (what is it?), stream 1 - type 0x00000002 (VIDEO_MPEG2) and stream 2 - 0x50 (AUDIO_MP2). Mythtv detects and treats stream 0 as MPEG1 video with bitrate 0. This should be fixed at stream type detection stage, but I can't find where it is done :-) I put some additional checks in avformatdecoder.cpp preventing video streams with bitrate 0 from playing. This check should be helpful with other situations when stream type is misrecognized.

Attached file is avformatdecoder.diff against svn trunk rev 16804.

This is temporary fix, maybe someone find better solution? (at stream type detection stage).

Changed 12 years ago by dluzin@…

Attachment: avformatdecoder.diff added

Temporary fix

Changed 12 years ago by dluzin@…

Attachment: avformatdecoder.2.diff added

This one should be readable

comment:3 Changed 11 years ago by stuartm

Milestone: unknown0.22

comment:4 Changed 11 years ago by stuartm

Component: mythtvVideo Playback
Owner: changed from Isaac Richards to stuartm
Status: newaccepted
Summary: Some DVB-S channels can't be played by mythfrontend.AVFormat Decoder attempts to play zero bitrate video streams

comment:5 Changed 11 years ago by stuartm

The following from the ffmpeg documentation means I'm not sure about the proposed fix - "bit_rate: 0 or some bitrate if this info is available in the stream". The implication being that there will be times when valid streams report a bitrate of zero.

A better solution would be to look at the bitrate of all video streams first and only ignore the zero bitrate stream if a non-zero stream can be found. This could only be done if ScanStreams? is reorganised, which is a good idea anyway, but it needs some discussion with the over devs first.

comment:6 Changed 11 years ago by stuartm

Owner: changed from stuartm to janneg
Status: acceptedassigned

comment:7 Changed 11 years ago by Janne Grunau

Milestone: 0.220.21.1
Owner: changed from janneg to Janne Grunau
Status: assignedaccepted

comment:8 Changed 10 years ago by stuartm

Milestone: 0.21.10.22

comment:9 Changed 10 years ago by stuartm

See #6122, a DVB radio channel which includes an mpeg-2 video stream with reported bitrate of 90Kbps.

comment:10 Changed 10 years ago by stuartm

Component: Video PlaybackMythTV - Video Playback

comment:11 Changed 10 years ago by Janne Grunau

Milestone: 0.22unknown
Priority: criticalminor
Status: acceptedinfoneeded

please recheck if the the problem still persist with current trunk and reupload the samples.

comment:12 Changed 10 years ago by stuartm

Resolution: invalid
Status: infoneededclosed

30 days without response.

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