Plan to support for custom encoder like rav1e instead of aom ? about libavif

[joedrago]

I implemented basic rav1e support today. If you read/execute rav1e.cmd in ext/, you should be able to build with -DAVIF_CODEC_RAV1E=1 -DAVIF_LOCAL_RAV1E=1 and it'll find the library and link against it.

I've only tested on windows-msvc (2017) and macOS Catalina.

[joedrago]

I don't have any specific plans right now to add any codecs, but I'm certainly not against it.

The pattern I put in place when I added dav1d would translate well to an encoder-only codec; I would just make it so that enabling it would override the encoding role from libaom, and if enabled in conjunction with dav1d, would avoid aom entirely.

[AurelC2G]

Thanks for working on this!

I noticed a small issue with how you pass quantizer values to rav1e:

    int minQuantizer = AVIF_CLAMP(encoder->minQuantizer, 0, 63);
    int maxQuantizer = AVIF_CLAMP(encoder->maxQuantizer, 0, 63);
    if (alpha) {
        minQuantizer = AVIF_QUANTIZER_LOSSLESS;
        maxQuantizer = AVIF_QUANTIZER_LOSSLESS;
    }
    if (rav1e_config_parse_int(rav1eConfig, "min_quantizer", minQuantizer) == -1) {
        goto cleanup;
    }
    if (rav1e_config_parse_int(rav1eConfig, "quantizer", maxQuantizer) == -1) {
        goto cleanup;
    }

Values for min/max quantizer in libavif are in the [0, 63] range, but in rav1e they are in [0, 255] (see https://github.com/xiph/rav1e/blob/master/src/capi.rs#L490), so clamping like you are here restricts the encoder to a small range of quantizer values.

[dreampiggy]

I've have a test on current ra1ve and aom on macOS 10.15. It seems rav1e encoding AVIF for this kids_720p.avif is 50 times faster 🤣 (aom need 1 minutes with 200% CPU Core, rav1e need just 2 seconds with just 100% CPU Core).

It's now really acceptable to make it possible for Client-User side program to integrate this. Previously my test programe just disable the AVIF encoding :)

[joedrago]

Excellent catch on the QP, I believe I've fixed it here:

0abf3b3

And yes, I was pleasantly surprised at rav1e's speed as well. If someone builds colorist (a tool of mine that uses libavif) with both rav1e and aom, I choose rav1e for encoding if aom isn't explicitly specified.