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Activity Forums Compression Techniques .flv sorenson + 16:9 AVI source = headache

  • .flv sorenson + 16:9 AVI source = headache

    Posted by Gav Bott on September 17, 2008 at 7:01 am

    I have a nasty little job that is well out of my usual confort zone (giving it to someone who knows what they are doing) – any help is aprecitaed.

    I have a number of AVI’s that need to be heavily compressed into .flv

    End frame size is 412×300

    The end file size is very restriced to about 1.5 meg / minute.

    My source files were all shot 16:9 so some cropping has to occur.

    If anyone can help me with some steps to try for best results I would be very grateful. Thought that a one step sorenson would be best but I’m getting terrible results.

    The Brit in Brisbane
    The Pomme in Production – Brisbane Australia.

    Gav Bott replied 17 years, 7 months ago 2 Members · 4 Replies
  • 4 Replies
  • Daniel Low

    September 17, 2008 at 1:16 pm

    Nasty indeed:

    Not only is the frame size neither 4:3 or 16:9 it’s also way to big for the data-rate you’ve been restricted to (approx 200Kbits/s for both audio and video)

    I guess this is one of those jobs where the clients web designer is telling you what frame size to use so it fits in their page, rather than you giving them some correct frame sizes and them building the page around one of them….

    If you really are totally restricted to that frame size and frame rate there’s little you can do about picture quality as it’ll look pretty rubbish unless the content is almost totally static!

    I suggest letterboxing the 16:9 clips into the frame rather than cropping, this in turn will reduce the active picture area making it a little easier to get better quality encode at the given datarate.

    Obviously use 2pass VBR if you can.

    Allocate the minimum datarate you can get away with for the audio….32kb/s?

    Even following all that, the encodes are unlikely to look very good.

    So, either reduce the frame size to something more suitable (and at the correct aspect ratio), or increase the bitrate, or a bit of both!

    __________________________________________________________________
    Please post back saying what solved your problem. It could help others, and saying ‘thanks’ is free!

  • Gav Bott

    September 18, 2008 at 3:38 am

    Thanks for the advice.

    The evil web designer has given me the frame size to use as you worked out.

    Any thoughts on what frame size I could compress to that he will then enlarge to fit his (totally arbitrary I suspect) design? Am I better off doing it this way round than just rendering to his spec?

    Thanks

    The Brit in Brisbane
    The Pomme in Production – Brisbane Australia.

  • Daniel Low

    September 18, 2008 at 7:07 am

    With Flash, it’s better to encode to his size than have him resize your video. You should still letterbox it.

    __________________________________________________________________
    Please post back saying what solved your problem. It could help others, and saying ‘thanks’ is free!

  • Gav Bott

    September 18, 2008 at 11:21 pm

    Thanks for the advice Dan

    The Brit in Brisbane
    The Pomme in Production – Brisbane Australia.

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