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Thread: Add logo, preserve bitrate -> less quality stream

  1. #1

    Default Add logo, preserve bitrate -> less quality stream

    Hi,
    I'd like to use the transcoder to add a logo to the stream while preserving all other audio/video parameters
    (e.g. <FitMode>match-source</FitMode>, <Bitrate>${SourceVideoBitrate}</Bitrate>), however the resulting stream is of much less quality.
    Is this normal?
    What should I do to get a better resulting stream?
    Thanks

  2. #2
    Join Date
    Dec 2007
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    I would experiment with different image sizes, and template /Overlay settings.

    Richard

  3. #3

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    I'd like to preserve video file parameters (width, height, bitrate, etc.).
    I understand that in order to renderize the logo image on the video surface, the video stream must be decoded and then re-encoded, but the resulting quality is not good compared to the incoming stream.

  4. #4
    Join Date
    Dec 2007
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    21,962

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    What encoder and what are the encoding details of the source stream? Are you transcoding anything? Since you are not changing bitrate, is the only purpose adding the graphic?

    Richard

  5. #5

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    The source stream is generated by Wowza, I'm using the technique detailed in
    http://www.wowza.com/forums/content....tching-example
    in order to get Wowza stream a sequenze of video files.
    All video files are encoded with ffmpeg: 640x360, 25fps, h264/736Kbps, aac/128Kbps, the quality is good.
    Everything works fine, but I need to add a logo image.
    So I'm using the transcoder to generate a second stream with the same bitrate and the logo image.
    If I set the transcoder to match the source bitrate, i.e. <Bitrate>${SourceVideoBitrate}</Bitrate>, than the quality is poor, while if I set explicitly the transcoder bitrate, i.e. <Bitrate>736000</Bitrate> than the quality is better (but a little worst than the source stream, probably caused by the re-encoding to add the logo image).
    Therefore It would seem that Wowza doesn't correctly detect the source bitrate (in this particular case where I'm generating a stream from video files) and use some default value. Could this be correct?
    Thanks

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