Mailing List Archive: MythTV: Dev

Mytharchivehelper and streaminfo problems

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otto at kolsi

Jan 27, 2008, 2:27 AM

Post #1 of 4 (566 views)
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Mytharchivehelper and streaminfo problems

Some recorded files cause problems in MythArchive because video
resolution is detected as 0x0. Timings/lengths might also be wrong.

I did a simple script to create streaminfo files for all the recordings
that I currently have. These are all DVB-T recordings, some have several
audio, some several dvb subtitle tracks and some have data tracks.

Out of 388 recordings there are 59 (15%) that produce 0x0 video
resolution when analyzed with mytharchivehelper (with method 2). I've
attached 2 example outputs.

Rebuilding seektable doesn't help and these recordings can be watched
just fine. Quickly looking at mytharchivehelper it seems that stream
info comes from "av_find_stream_info(inputFC)".

Is this just ffmpeg problem or can something be done in
mytharchivehelper? It would probably be good to have some more checks in
mythburn.py for these kind of problematic resolutions and timing values.
--
Otto

Attachments:

1007_20071208164000.mpg.xml (0.77 KB)

1001_20080126203000.mpg.xml (0.62 KB)

mythtv at dsl

Jan 27, 2008, 2:56 PM

Post #2 of 4 (512 views)
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Re: Mytharchivehelper and streaminfo problems [In reply to]

Otto Kolsi wrote:
>
> Some recorded files cause problems in MythArchive because video
> resolution is detected as 0x0. Timings/lengths might also be wrong.
>
> I did a simple script to create streaminfo files for all the
> recordings that I currently have. These are all DVB-T recordings, some
> have several audio, some several dvb subtitle tracks and some have
> data tracks.
>
> Out of 388 recordings there are 59 (15%) that produce 0x0 video
> resolution when analyzed with mytharchivehelper (with method 2). I've
> attached 2 example outputs.
>
> Rebuilding seektable doesn't help and these recordings can be watched
> just fine. Quickly looking at mytharchivehelper it seems that stream
> info comes from "av_find_stream_info(inputFC)".
>
> Is this just ffmpeg problem or can something be done in
> mytharchivehelper? It would probably be good to have some more checks
> in mythburn.py for these kind of problematic resolutions and timing
> values.
Like you say mytharchivehelper just relies on the stream info returned
from the avformat library.

If you play the file using 'ffplay -stats FILENAME' does the dump stream
info thats displayed show the correct resolution and does that differ
from the dump stream info displayed when mytharchivehelper is run?

If the file duration is wrong when using method 2 then that suggests
either the position map in the DB is wrong or the method used to
calculate the duration from the position map is wrong . The script
always uses method 1 when it need an accurate duration because it is
guaranteed to get the proper file duration because it counts the video
frames.

It should be possible to change mytharchivehelper to decode a few video
frames and get the resolution that way if necessary.

Paul H.
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otto at kolsi

Jan 28, 2008, 11:35 AM

Post #3 of 4 (496 views)
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Re: Mytharchivehelper and streaminfo problems [In reply to]

Paul Harrison wrote:
> Otto Kolsi wrote:
>> Some recorded files cause problems in MythArchive because video
>> resolution is detected as 0x0. Timings/lengths might also be wrong.
>
> If you play the file using 'ffplay -stats FILENAME' does the dump stream
> info thats displayed show the correct resolution and does that differ
> from the dump stream info displayed when mytharchivehelper is run?

I fetched and compiled fresh ffmpeg ([11634]) and tried ffplay with
several problematic recordings. In all cases ffplay dumps valid
resolution. I've attached one example where is relevant parts of data
from mytharchive, streaminfo.xml and ffplay.

> It should be possible to change mytharchivehelper to decode a few video
> frames and get the resolution that way if necessary.

This is just guessing, but would it be possible to advance the position
from where the stream info is fetched? So that if we don't receive valid
info, try 3-5 times and each time go bit further? If the beginning of
the stream is somehow corrupted and working values can be fetched little
bit further..
--
Otto

Attachments:

fileinfo.txt (0.90 KB)

mythtv at dsl

Feb 3, 2008, 2:26 AM

Post #4 of 4 (480 views)
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Re: Mytharchivehelper and streaminfo problems [In reply to]

Otto Kolsi wrote:
> Paul Harrison wrote:
>> Otto Kolsi wrote:
>>> Some recorded files cause problems in MythArchive because video
>>> resolution is detected as 0x0. Timings/lengths might also be wrong.
>>
>> If you play the file using 'ffplay -stats FILENAME' does the dump stream
>> info thats displayed show the correct resolution and does that differ
>> from the dump stream info displayed when mytharchivehelper is run?
>
> I fetched and compiled fresh ffmpeg ([11634]) and tried ffplay with
> several problematic recordings. In all cases ffplay dumps valid
> resolution. I've attached one example where is relevant parts of data
> from mytharchive, streaminfo.xml and ffplay.
>
>> It should be possible to change mytharchivehelper to decode a few video
>> frames and get the resolution that way if necessary.
>
> This is just guessing, but would it be possible to advance the
> position from where the stream info is fetched? So that if we don't
> receive valid info, try 3-5 times and each time go bit further? If the
> beginning of the stream is somehow corrupted and working values can be
> fetched little bit further..

Otto any chance of cutting the first minute or two from a problem file
and providing it for download somewhere?

Paul H.

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