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Thread: avconv mov to flv

  1. #11
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    Re: avconv mov to flv

    Andrew gave some good advice too. Although I disagree with his view that he isn't an expert.

    You should change one thing: don't use -q:v with libx264. Use -crf instead. See the crf section in the FFmpeg and x264 Encoding Guide. It has examples and explanations.

    You may encounter two problems with your command, depending on your input. If -1 from your scale filter ends up being an odd value libx264 may complain, "height not divisible by 2". This can be an alternative method:
    Code:
    scale="320:trunc(ow/a/2)*2"
    IIRC, if height ends up being an odd value it will automatically round down to an even value. You can do the same for width too:
    Code:
    scale="trunc(oh*a*2)/2:240"
    The other potential issue is that flv container probably only accepts certain MP3 audio sample rates. ffmpeg, by default, will usually inherit the input sample rate for the output. If you end up with 48000 for example, then ffmpeg will complain:
    Code:
    FLV does not support sample rate 48000, choose from (44100, 22050, 11025)

  2. #12
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    Re: avconv mov to flv

    Quote Originally Posted by FakeOutdoorsman View Post


    The other potential issue is that flv container probably only accepts certain MP3 audio sample rates. ffmpeg, by default, will usually inherit the input sample rate for the output. If you end up with 48000 for example, then ffmpeg will complain:
    Code:
    FLV does not support sample rate 48000, choose from (44100, 22050, 11025)
    FakeOutdoorsman, you called that one!

    So, I thought to myself this is great. I saved the command as a script and put it in the aliases file and hoped I was ready to go.

    Sure enough, the first time out going from mpg to flv using:
    Code:
    ffmpeg -i foo.mpg \
           -c:v libx264 -crf 5 -vf scale=320:-1 \
           -c:a libmp3lame -q:a 3 \
           MPEG-to-libx264.flv
    I got the sample rate error.

    My question is where in the command do I specify the sample rate?



    Thank you for the help! I really do appreciate it!!
    Last edited by GrouchyGaijin; January 4th, 2013 at 12:08 AM. Reason: Deleted a second question that I found the answer to
    Thank you,
    GG -----------
    GUI we don't need no stinking GUI: A collection of Bash scripts
    Mutt (email), cmus (music),Google Calendar and Google Tasks cli

  3. #13
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    Re: avconv mov to flv

    You can add "-ar" as an output option which is anywhere after "-i foo.mpg", such as:
    Code:
    ffmpeg -i foo.mpg \
           -c:v libx264 -crf 23 -vf scale=320:-1 \
           -c:a libmp3lame -q:a 3 -ar 44100 \
           MPEG-to-libx264.flv
    I also changed your -crf value in this example. -q:v and -crf are not interchangeable, so although -q:v 5 might be a good balance for your input and the flv1 encoder, a value of -crf 5 will result in an unnecessarily large output. The link in my last post shows how to use crf. Default value is 23, which is what libx264 will use if you omit -crf. Use the highest value that still provides an acceptable quality.

  4. #14
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    Re: avconv mov to flv

    What does -q:v do in relation to libx264?

  5. #15
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    Re: avconv mov to flv

    Probably nothing. I think it is ignored, and possibly limited to the mpeg quant scale (flv/h263/h263+/mpeg1video/mpeg2video/mpeg4/mjpeg/msmpeg*), but I might be wrong about that.
    Last edited by FakeOutdoorsman; January 4th, 2013 at 01:13 AM.

  6. #16
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    Re: avconv mov to flv

    Why not simply get a Dropbox or other cloud account, upload your mov files, send grandparents an email with attachments. They can download and watch mov files with vlc.

  7. #17
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    Re: avconv mov to flv

    Quote Originally Posted by JimS View Post
    Why not simply get a Dropbox or other cloud account, upload your mov files, send grandparents an email with attachments. They can download and watch mov files with vlc.
    Is this a real suggestion or are you making a joke?
    Thank you,
    GG -----------
    GUI we don't need no stinking GUI: A collection of Bash scripts
    Mutt (email), cmus (music),Google Calendar and Google Tasks cli

  8. #18
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    Re: avconv mov to flv

    Joodan ja nai!
    I've done it my way after reducing my camera images with ffmpeg.
    And then I sent them to relatives via email attachments from Dropbox.
    It works and it is free. Quality isn't the best.
    I'm not running a webserver, so I can't help you there. Good luck.
    MVH
    JimS
    ...

  9. #19
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    Re: avconv mov to flv

    Quote Originally Posted by GrouchyGaijin View Post
    Is this a real suggestion or are you making a joke?
    It was a simple but great suggestion. Why not?
    Overclocked HPML150 running Precise Pangolin 12.04 LTS

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