Average bit rate?

1. offizieller Beitrag

    Hi, new to Voukoder, I am using it to export from Ae on a Win 10 machine. Taking advantage of the multi frame rendering.

    I have tried average bit rate which I assume is akin to variable bit rate in Media Encoder, but haven't got it to work. Nothing is exported.

    Two questions:

    • What are some decent settings for average bit rate? For client export and client review. h.264, mp4.
    • Why is constant quantizer on all the standard settings? I haven't been able to find a good explanation of what it is online.

    Thank you.

  • Vouk 18. November 2021 um 07:26

    Hat das Thema freigeschaltet.
    • Offizieller Beitrag

    Normally you just use "bitrate" based settings if you aim for a specific file size (i.e. the file has to fit on a DVD or USB drive). If you don't care about the file size (like you want to upload the file to YouTube or similar) you are using quantizer (~ quality) based rate control mechanisms like CRF or CQ(P).

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    Hi Vouk! Thank you for replying.

    Use cases for me for small files are emailing review versions.

    I am an animator and motion designer, working on short ads etc. Also the internet is slow around here compared to Europe and the US.

    Is there any where you might point me to to learn further about these terms? ABR, CRF or CQ(P).

    Cheers!

    Zitat von tilborg

    Hi Vouk! Thank you for replying.

    Use cases for me for small files are emailing review versions.

    I am an animator and motion designer, working on short ads etc. Also the internet is slow around here compared to Europe and the US.

    Is there any where you might point me to to learn further about these terms? ABR, CRF or CQ(P).

    Cheers!

    Emailing video is not really a good idea (I remember there are 25MB file size limit), but you can try shrink resolutions; use OneDrive/GoogleDrive to share larger videos; or build a public torrent transmission and email just the torrent file to the client

    Zitat von tilborg

    Is there any where you might point me to to learn further about these terms? ABR, CRF or CQ(P).

    I recommend Werner Robitza's Understanding Rate Control Modes (x264, x265, vpx) article for a quick-ish rundown.

    Using H.264, H.265, and VP8/9 codec specs for reference...

    Average Bit Rate (ABR)

    A.K.A Target Bitrate

    Like the other modes you mentioned, this is a variable bit rate (VBR) mode.

    If you have time to kill and you want to maximize quality, you can also employ 2-pass encoding. This pre-analyzes footage to find the best way to quantize and store its data.

    This mode indirectly controls quality, is often paired with an optional Max Bit Rate, and has no minimum bit rate. As Vouk said, setting this parameter is the best for outputting to a certain file size.

    Resolution, color bit depth, and frame rate are the most important factors when considering video bit rate. Consider the duration/length as well when you want a specific file size.

    Constant Rate Factor (CRF)

    Control the bit rate to achieve a specified visual quality. This is rather self-explanatory, but be warned that it may remove small details that it believes are unwanted artifacts. Note: Lower number == higher quality.

    Constant Quantization Parameter (CQP)

    This is a more literal "constant quality" mode. It is generally not recommended because CRF does the same thing, but with better quality and file sizes.

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    Whenever I have a question about a particular codec's parameters, I tend to turn to its documentation within FFMpeg's documentation and, of course, search engines.