Package 

Class EncodingConfig

  • 
public final class EncodingConfig

    https://ffmpeg.org/ffmpeg-all.html

    https://video.stackexchange.com/a/24684

    The frames in your H.264 video are grouped into units called GOPs (Group Of Pictures). Inside these GOPs frames are classified into three types:

    I-frame: frame that stores the whole picture P-frame: frame that stores only the changes between the current picture and previous ones B-frame: frame that stores differences with previous or future pictures

    Additionally, I-frames can be classified as IDR frames and non-IDR frames.

    The difference is that frames following an IDR frame cannot reference any frame that comes before the IDR frame, while in the case of a non-IDR frame there are no limitations.

    Every GOP starts with an I-frame, also called a keyframe, but may contain more than one. To create further confusion, a GOP can start with an IDR frame or with a non-IDR frame. This means that frames in the GOP can sometimes refer to previous GOPs (in this case the GOP is said to be "open"), and sometimes not (in this case it's closed).

    It's common to see the structure of a GOP represented as in this example: IBBBPBBBPBBBI. Here the length of the the GOP is 12 frames, with 3 B-frames between each P-frame.

    • Method Detail

      • getKeyInt

         final Integer getKeyInt()

        keyInt specifies the maximum length of the GOP, so the maximum interval between each keyframe, which remember that can be either an IDR frame or a non-IDR frame. I'm not completely sure but I think that by default ffmpeg will require every I-frame to be an IDR frame, so in practice you can use the terms IDR frame and I-frame interchangeably

      • getMinKeyInt

         final Integer getMinKeyInt()

        min-keyint specifies the minimum length of the GOP. This is because the encoder might decide that it makes sense to add a keyframe before the keyint value, so you can put a limit.

      • getVideoQuality

         final Integer getVideoQuality()

        crf Set the quality/size tradeoff for constant-quality (no bitrate target) and constrained-quality (with maximum bitrate target) modes. Valid range is 0 to 63, higher numbers indicating lower quality and smaller output size. Only used if set; by default only the bitrate target is used.

        0 for lossless, 23 is default in ffmpeg

        reasonable value 18

      • getSourceFrameRate

         final Float getSourceFrameRate()

        -framerate input Frame rate of the video. https://lists.ffmpeg.org/pipermail/ffmpeg-user/2013-July/016273.html

      • getOutputFrameRate

         final Float getOutputFrameRate()

        -r output Frame rate of the video. https://video.stackexchange.com/a/13074

      • getPixelFormat

         final PixelFormat getPixelFormat()

        pix_fmts A ’|’-separated list of pixel format names, such as "pix_fmts=yuv420p|monow|rgb24".

      • getPreset

         final Preset getPreset()

        -preset type Configuration preset. This does some automatic settings based on the general type of the image.

        https://trac.ffmpeg.org/wiki/Encode/H.264

      • getMaxrate

         final Integer getMaxrate()

        https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate specifies a maximum tolerance. this is only used in conjunction with bufsize

        reasonable value for full hd = 8 * 1024

      • getBufsize

         final Integer getBufsize()

        specifies the decoder buffer size, which determines the variability of the output bitrate

        reasonable value for full hd = 8 * 1024