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  1. Member Klagar's Avatar
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    Hi !

    First of all, sorry for any enthusiast who thought I was about to start a discussion over whether it would be best to use FFMPEG on Windows or Linux... Not gonna happen !

    Rather, I have some questions regarding compatibility issues. I heard that, some tests having been made, there were major differences in the way one uses FFMPEG on either OS.

    For example, someone told me the -treillis parameter had to be set to 1 whenever one encoded on Windows, or to 0 if encoding on Linux (or maybe the opposite, he wasn't very clear on the subject :S), otherwise the encoding would just plain not work.

    Another example : the -qmin/-qmax parameters would typically accept values ranging from 1 (or 0 ?) to 31, or up to 51 when encoding to H264. That was on Wiondows. But the same person told me that for some reason, they never could set this parameter higher than 30 when encoding on Linux.

    One last example : I heard (haven't had a chance to test it out yet, still waiting for Linux to get installed on my machine) that the -qcomp parameter works in Windows only, not in Linux.

    So the question is as follows : first, can anyone confirm or invalidate those informations, preferably with some reason or explanation ? And second, are there any other examples of parameters which should react differently when using one or the other OS ? Or alternatively, is there some way to prevent such incompatibility from occurring ?

    Thanks as always !
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  2. Originally Posted by Klagar View Post
    Hi !
    ... ... ...
    For example, someone told me the -treillis parameter had to be set to 1 whenever one encoded on Windows, or to 0 if encoding on Linux (or maybe the opposite, he wasn't very clear on the subject :S), otherwise the encoding would just plain not work.

    So the question is as follows : first, can anyone confirm or invalidate those informations, preferably with some reason or explanation ? And second, are there any other examples of parameters which should react differently when using one or the other OS ? Or alternatively, is there some way to prevent such incompatibility from occurring ?

    Thanks as always !
    I wud consider trellis as an option specific to particular codecs, not to OS.
    I have been using trellis successfully in both OS.
    trellis to me, as a codecs specific option is...
    trellis 0 = no trellis
    trellis 1 = trellis on final encode

    Leave it to the readers to know by self which specific codecs are using trellis
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  3. Explorer Case's Avatar
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    Originally Posted by Klagar View Post
    Another example : the -qmin/-qmax parameters would typically accept values ranging from 1 (or 0 ?) to 31, or up to 51 when encoding to H264. That was on Wiondows. But the same person told me that for some reason, they never could set this parameter higher than 30 when encoding on Linux.
    I don't know about Windows vs Linux, but the quantizer range is recommended as 2-9 by some for MPEG-4 Visual (mpeg-4 part 2), as Qmax=30 would allow for near-maximum compression, thus the lowest possible quality, far below what anyone would find acceptable. On the other side of the spectrum, Qmin=1 would allow the encoder to use much more bitrate than Qmin=2, while the viewer wouldn't be able to notice a better quality.
    For H.264, my ffmpeg/x264 enabled encoder GUI advices Qmin=10.
    My point being to stay away from the extremes in the range, as the output will not benefit from it. Which is why you can set the range in the first place. If the full quantizer range would always be available to the encoder, then there would be no reason to set a custom range.
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  4. Member Klagar's Avatar
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    Thanks for your answers !

    Turns out we were just not using the same version of FFmpeg on each OS. Windows has WinFF installed, so the related FFmpeg version would be a SVN-something. Linux uses another one. That must be the cause of the incompatibility.

    Although this rises a new question as to the real differences between those versions, but I've seen already there is little to no documentation at all concerning ancient FFmpeg versions (our Windows one is dated 2009) and I reckon this is rather pointless, as I should probably instead suggest that updates be made and that we use the same version on al our machines.
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