Changes between Version 2 and Version 3 of ChangingFrameRate


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Timestamp:
Oct 13, 2018, 3:03:55 PM (5 weeks ago)
Author:
slhck
Comment:

formatting

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  • ChangingFrameRate

    v2 v3  
    28282. With the [http://ffmpeg.org/ffmpeg-filters.html#fps fps filter] 
    2929 
    30 There are differences in implementation of those two; `-r` takes effect after all filtering but before encoding of the video stream has taken place. Its logic depends on the video sync method set (`-vsync`). For an output format like MP4, which defaults to constant frame rate (CFR), `-r` will generate a CFR stream. For variable frame rate formats, like Matroska, the `-r` value acts as a ceiling, so that a lower frame rate input stream will pass through, and a higher frame rate stream, will have frames dropped, in order to match the target rate. The `-r` value also acts as an indication to the encoder of how long each frame is, and can affect the ratecontrol decisions made by the encoder. 
     30There are differences in implementation of those two: 
    3131 
    32 `fps`, as a filter, needs to be inserted in a filtergraph, and will always generate a CFR stream. It offers five rounding modes that affect which source frames are dropped or duplicated in order to achieve the target framerate. See the [http://ffmpeg.org/ffmpeg-filters.html#fps documentation] of the fps filter for details. 
     32*  `-r` takes effect after all filtering, but before encoding of the video stream has taken place. 
     33* The `-r` logic depends on the video sync method set (`-vsync`). 
     34* For an output format like MP4, which defaults to constant frame rate (CFR), `-r` will generate a CFR stream. For variable frame rate formats, like Matroska, the `-r` value acts as a ceiling, so that a lower frame rate input stream will pass through, and a higher frame rate stream, will have frames dropped, in order to match the target rate. 
     35* The `-r` value also acts as an indication to the encoder of how long each frame is, and can affect the ratecontrol decisions made by the encoder. 
     36* `fps`, as a filter, needs to be inserted in a filtergraph, and will always generate a CFR stream. It offers five rounding modes that affect which source frames are dropped or duplicated in order to achieve the target framerate. See the [http://ffmpeg.org/ffmpeg-filters.html#fps documentation] of the fps filter for details. 
    3337 
    3438In the following we will focus on using the `fps` filter, as it is more configurable.