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  1. Member
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    Jan 2019
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    hawai
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    i have one video 1280x720 with very excellent quality video and small size, only 548MB
    sometimes i need to convert some video on another format to play on my TV.
    for this i use ffmpeg and convert on mp4 with mpeg4 codec or libxvid codec with VBR quality set to 4 or 5.
    but big bitrate (2500-3000) are cause to big file (for 120 minutes 1,6-1,8 GB)
    this video (nice quality for me) have same duration (120 min) but small size (only 534MB). which codec was used and with what parameters (with ffmpeg)
    to get such a small final file?
    here video information:

    Code:
    General
    Complete name                            : E:\film\REYKJAVIK - ROTTERDAM.mp4
    Format                                   : MPEG-4
    Format profile                           : Base Media / Version 2
    Codec ID                                 : mp42 (isom/mp42)
    File size                                : 535 MiB
    Duration                                 : 1 h 22 min
    Overall bit rate mode                    : Variable
    Overall bit rate                         : 907 kb/s
    Encoded date                             : UTC 2018-11-27 22:31:19
    Tagged date                              : UTC 2018-11-27 22:31:19
    gsst                                     : 0
    gstd                                     : 4954186
    
    Video
    ID                                       : 1
    Format                                   : AVC
    Format/Info                              : Advanced Video Codec
    Format profile                           : Main@L3.1
    Format settings                          : CABAC / 3 Ref Frames
    Format settings, CABAC                   : Yes
    Format settings, Reference frames        : 3 frames
    Codec ID                                 : avc1
    Codec ID/Info                            : Advanced Video Coding
    Duration                                 : 1 h 22 min
    Bit rate                                 : 775 kb/s
    Width                                    : 1 280 pixels
    Height                                   : 720 pixels
    Display aspect ratio                     : 16:9
    Frame rate mode                          : Constant
    Frame rate                               : 25.000 FPS
    Color space                              : YUV
    Chroma subsampling                       : 4:2:0
    Bit depth                                : 8 bits
    Scan type                                : Progressive
    Bits/(Pixel*Frame)                       : 0.034
    Stream size                              : 458 MiB (85%)
    Title                                    : ISO Media file produced by Google Inc. Created on: 11/27/2018.
    Encoded date                             : UTC 2018-11-27 22:31:19
    Tagged date                              : UTC 2018-11-27 22:31:19
    Color range                              : Limited
    Color primaries                          : BT.709
    Transfer characteristics                 : BT.709
    Matrix coefficients                      : BT.709
    Codec configuration box                  : avcC
    
    Audio
    ID                                       : 2
    Format                                   : AAC LC
    Format/Info                              : Advanced Audio Codec Low Complexity
    Codec ID                                 : mp4a-40-2
    Duration                                 : 1 h 22 min
    Bit rate mode                            : Variable
    Bit rate                                 : 128 kb/s
    Channel(s)                               : 2 channels
    Channel layout                           : L R
    Sampling rate                            : 44.1 kHz
    Frame rate                               : 43.066 FPS (1024 SPF)
    Compression mode                         : Lossy
    Stream size                              : 75.6 MiB (14%)
    Title                                    : ISO Media file produced by Google Inc. Created on: 11/27/2018.
    Language                                 : English
    Encoded date                             : UTC 2018-11-27 22:31:19
    Tagged date                              : UTC 2018-11-27 22:31:19
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  2. Video codec is avc which is widely supported by hardware

    It's not possible to re-encode a highly compressed file, and keep both quality AND filesize constant, especially when using the same (ex: x264) or a less efficient video codec.
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  3. Ffmpeg with libx264 and crf 24-26
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  4. Member
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    @butterw
    i don't want re-encode this file. this file is great like this. i want information for some other video, ex 1,3-1,5GB to know how to get a final file similar to this, with great definition and small in size... then to have this final result it's thanks to codec x264? with mpeg4 would i get larger files (for the same bitrate)?

    @ProWo
    what is crf 24-26?
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  5. h264/x264 is a mpeg4-avc codec (as opposed to older mpeg4-asp codecs like xvid).

    crf is the single pass encoding setting used by x264, lower means higher quality (ex: crf 23) and higher bitrate.
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  6. Member
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    ok. many tanxs for your reply. regards.
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  7. Member DB83's Avatar
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    Codec does not affect file size.


    Simple formula. It's called the 1st commandment of Vhelp. File size = runlength * bitrate. So in your example you can, theoretically, duplicate the result by adopting that bitrate with whatever codec you chose.
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  8. Originally Posted by lomero View Post
    @ProWo
    what is crf 24-26?
    Try my clever FFmpeg-GUI, load the file you want encode, in the video convert section set x264 as encoder and crf 24 and then encode.
    Try with other crf values too, until you get the desired result.
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  9. Member
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    ok thank you both
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  10. If you enncode with ffmpeg using libx264 with crf of 24 the file size will be about half size if you change the -preset from ultrafast to slow. However the encoding time will be 60 times higher.
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