media file with data corruption

[cristian]

Hello,
I am trying to make a gstreamer application that detects corrupted files(for example a mp3 file). I don't have so much experience, if anyone can tell me where to look or investigate to make my program work!
I guess , I'm not sure, but does it have something to do with filters?

Cristi.

[cristian]

Does gstreamer have any tools in analyzing the samples of an audio stream? For example I have a bad audio file and some chuncks of data doesn't play natural. Does anyone have an ideea how to detect such an anomally?

[Edward Hervey]

On Tue, 2010-10-12 at 23:54 -0700, cristiurban wrote:
> Hello,
> I am trying to make a gstreamer application that detects corrupted files(for
> example a mp3 file). I don't have so much experience, if anyone can tell me
> where to look or investigate to make my program work!
> I guess , I'm not sure, but does it have something to do with filters?

  We don't have a (unified) way for plugins (like demuxers, decoders,
parsers) to report stream corruption. Most of those are only emitted via
logging warnings and plugins will do their best to recover from them. If
the file is *really* corrupt (i.e. unrecoverable playback error), then
an ERROR will be posted on the bus.

  You could of course modify the mp3parse element to detect such
corruptions and report them some way or another (like via messages on
the bus). You'd need knowledge about the format though, and I'm not 100%
certain there's a checksum system that would allow you to detect whether
the stream is really corrupted or not.

   Edward

>
> Cristi.



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[Stefan Sauer]

Am 13.10.2010 09:54, schrieb cristiurban:
>
> Hello,
> I am trying to make a gstreamer application that detects corrupted files(for
> example a mp3 file). I don't have so much experience, if anyone can tell me
> where to look or investigate to make my program work!
> I guess , I'm not sure, but does it have something to do with filters?
>
> Cristi.

As edward wrote most 'issues' only appear in the log as
GST_{ERROR,WARNING,DEBUG,INFO,LOG} calls. Instead the plugins could use
GST_ELEMENT_{ERROR,WARNING,INFO} more and e.g. post a GstStreamError (e.g.
GST_STREAM_ERROR_FORMAT, GST_STREAM_ERROR_DEMUX or GST_STREAM_ERROR_DECODE). It
would be easy to add more codes.

You wound need to start looking at clips that are known to be wrong and check if
an error is posted, if not check if there is a log entry to see if the issue is
caught and then make a patch.

Stefan

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[Gruenke, Matt]

-----Original Message-----
From: Edward Hervey [mailto:[hidden email]]
Sent: Friday, October 15, 2010 04:20
To: Discussion of the development of GStreamer
Subject: Re: [gst-devel] media file with data corruption

<snip/>

>   We don't have a (unified) way for plugins (like demuxers,
> decoders, parsers) to report stream corruption. Most of those
> are only emitted via logging warnings and plugins will do their
> best to recover from them. If the file is *really* corrupt (i.e.
> unrecoverable playback error), then an ERROR will be posted on
> the bus.

We might propose mechanisms for indicating corrupt & incomplete frames.
Buffer flags are an obvious solution for incomplete frames (probably
need more than one flag, since frame might be missing beginning and/or
end).  They could also work for corrupt frames, although I can sort of
see some cases where sending an in-band event would be a better fit.


<snip/>


Matt


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