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  1. Member
    Join Date: Nov 2011
    Location: USA
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    Hi. I have searched for a solution, but without success. Maybe I am not looking for the correct thing or term. I am trying to save video output from FFplay for analysis. I am modifying some of the H.264 decoder source code in FFmpeg and then using FFplay to view the visual results by playing an mp4 video-only file containing H.264-encoded video data. However, I don't know how to save the FFplay output once I run FFplay. I'm thinking it is something similar to a dump.

    Alternatively, how can I use FFmpeg to play the file, view the video and save the output rather than just doing conversions, etc. in the console? It seems that there should be a way to call FFplay from FFmpeg and then save/dump the visual results.

    Thanks.
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  2. Member
    Join Date: Sep 2007
    Location: Canada
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    Why use FFplay at all? Why not use FFmpeg with your modified decoder to output a video for viewing later - ie. view that exported video in any media player (even FFPlay). You can use a lossless format in the same colorspace

    What am I missing ?
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  3. Member
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    Originally Posted by poisondeathray View Post
    Why use FFplay at all? Why not use FFmpeg with your modified decoder to output a video for viewing later - ie. view that exported video in any media player (even FFPlay). You can use a lossless format in the same colorspace

    What am I missing ?
    Hi. Thanks for your reply. How would I use FFmpeg to output a video for viewing later?
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  4. Member
    Join Date: Sep 2007
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    Originally Posted by qontranami View Post
    Originally Posted by poisondeathray View Post
    Why use FFplay at all? Why not use FFmpeg with your modified decoder to output a video for viewing later - ie. view that exported video in any media player (even FFPlay). You can use a lossless format in the same colorspace

    What am I missing ?
    Hi. Thanks for your reply. How would I use FFmpeg to output a video for viewing later?
    http://ffmpeg.org/ffmpeg.html

    ffmpeg -i input.ext -vcodec huffyuv -acodec copy output.avi

    For example this will output with huffyuv (lossless) compression - you need plenty of HDD space

    You could use other types of compression if you want, or even lossy compression depending on your goals - maybe a certain level of quality is enough for your purposes
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  5. Member
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    Alright. I will give this a try and report back.
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  6. Member
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    How is it possible that you know how to modify source code for ffmpeg's h264 decoder, yet not know how to use ffmpeg for encoding ??
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  7. Member
    Join Date: Nov 2011
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    Originally Posted by poisondeathray View Post
    How is it possible that you know how to modify source code for ffmpeg's h264 decoder, yet not know how to use ffmpeg for encoding ??
    Thanks for your continued responses. I'm not trying to do any encoding, which I have done before, actually. All I would like to do is just output a file so as to observe the visual effects resulting from modifying the decoder. It is important that I do not encode the decoder output so that I can perform quality analysis later. This where lossless output comes in, which I was a little fuzzy about.

    In any case, I was able to output a lossless file encapsulated as an avi according to your earlier suggestion. I played the video file and I was able to see what I wanted. Thank you very much. Eventually, I am going to save different versions of the same video based on different decoder modifications and then compare them quality-wise. I hope this all makes sense now.
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