Transcoding splitting files?

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2007-08-26
2013-05-30
  • Deivid Calles
    Deivid Calles
    2007-08-26

    Ive been having some trouble getting the transcoding to work on .9. I'm to the ponit now where I know the files I select are being passed through ffmpeg but they still won't play on the receiving device.

    I've looked into what mediatomb is doing once I run it.. I can see that if i play a file that requires transcoding, ffmpeg will run and start transcoding but it will keep spewing out this error message every few seconds:

    [mpeg1video @ 0xb7df6508]warning, clipping 1 dct coefficients to -255..255
    [mpeg1video @ 0xb7ec9508]warning, clipping 1 dct coefficients to -255..255
    [mpeg1video @ 0xb7df6508]warning, clipping 1 dct coefficients to -255..255
    [mpeg1video @ 0xb7ec9508]warning, clipping 1 dct coefficients to -255..255

    I've also noticed that each time one of these messages comes up if I look in /tmp (at where the transcode FIFO is), the stream starts being saved with a new name... I would have thought the whole video needs to be sent to a single location for it to play?

    So, I guess my questions are:

    Are those initial error messages normal?
    Is the cause of my problems the fact that the output keeps changing to a different location?

    FYI, I'm using Ubuntu 7.04 Feisty with a PS3 as the receiver.. I've been through all the PS3 related things and I'm fairly confident that this problem is down to the above... I'm not an expert though!

    If anyone wants me to add anything to this post jsut let me know.

    Thanks

     
    • Jin
      Jin
      2007-08-26

      Mmm, I think the problem that you are having is related to your ffmpeg script.

      Did you the "changing location" is probably the following: the transcoder aborts, the PS3 got some data and is confused, so it repeats the erquest. Each request spawns a new transcoder, i assume that's what is happening.

      I wrote a small howto here:
      http://www.deadlock.dhs.org/jin/mt-tr-howto.txt

      I suggest you do the command line test with the fifo, ffmpeg and mplayer and see if that works. I can not give you any detailed ffmpeg parameters yet, I never used it so I will have to read up on it and do some tests myself. Make sure, that when selecting an output format you pick one that is streamable, like MPEG1 or MPEG2, but not something in an .AVI container!

      Those ffmpeg errors should also not be that; so the problem you are seeing is related to your ffmpeg script and its transcoding parameters.

      Kind regards,
      Jin

       
    • Deivid Calles
      Deivid Calles
      2007-08-26

      Your guide is the one I used to get there. I initially used the ffmpeg script that you had in there but then changed to one I got from someone in the IRC channel. I'll give yours another try and see if I get the same problem.

      Something else I noticed too... When I go to watch on the PS3, I get my first ffmpeg thread, the TV goes black (as if loading the video) for a few seconds then gives the error. This is the point that my second ffmpeg script would kick in.

      Then, if I exit mediatomb in the PS3 XMB and just watch the terminal window it will carry on generating new ffmpeg threads as if mediatomb still believes it's streaming to the ps3. At the same time these threads will die and regenerate.. So by this time the PS3 is having no bearing on what's happening, it all looks to be coming from mediatomb or ffmpeg.

      I'll hunt around and see if there's anything bad with my ffmpeg but I don't think there is. It works absolutely fine if I create a FIFO using ffmpegtr.sh and play that back with mplayer.

       
    • Jin
      Jin
      2007-08-26

      Well, the stuff you describe (i.e. launching of several processes, etc.) is probably because the PS3 does several GET requests for whatever reason. Each HTTP GET will launch a transcoding process. Of course interesting *why* it is doing that; I already got one wireshark log where I could see something similar, but I would appreciate if you could also make one for me, particularly a log of what you described (i.e. when lots of ffmpeg threads are generated).

      I do have reports from PS3 users that they were able to watch whole movies with transcoding, so I guess it may really come down the ffmpeg parameters (i.e. to the format and specifics of the transcoded stream).
      I'd be very interested to figure this out, because we would like to offer some transcoding presets, so people would not have to mess with all the ffmpeg options themselves.

      Thanks,
      Jin

       
    • neotek
      neotek
      2007-08-26

      "...the TV goes black (as if loading the video) for a few seconds
      then gives the error."

      This is exactly what happens if you play a file with wrong audio- or video-codec parameters.
      If you need mp4/h264, i can post parameters that should work on ffmpeg. I have never transcoded mpg's by me self.
      try following: transcode one your movie with the same parameters your script uses in a file, copy them to the ps3 and play this file. If it is not working, you codec parameter are wrong.
      Sorry for this bad english :(