Change of encoding backend

[MimoKar]

Is there a possibility to change the encoding backend for AVIF from AOM to svt-av1 f.e?

[bigcat88]

Yes, it is supported. If you build pillow-heif from source and libheif has that backend enabled you can set preferred backend with these:

pillow_heif/pillow_heif/options.py

Lines 68 to 91 in 03c7beb

	PREFERRED_ENCODER = {
	"AVIF": "",
	"HEIF": "",
	}
	"""Use the specified encoder for format.
	You can get the available encoders IDs using ``libheif_info()`` function.
	When use pillow_heif as a plugin you can set this option with ``preferred_encoder`` key.
	.. note:: If the specified encoder is missing, the option will be ignored."""
	PREFERRED_DECODER = {
	"AVIF": "",
	"HEIF": "",
	}
	"""Use the specified decoder for format.
	You can get the available decoders IDs using ``libheif_info()`` function.
	When use pillow_heif as a plugin you can set this option with ``preferred_decoder`` key.
	.. note:: If the specified decoder is missing, the option will be ignored."""

here is even a test for it:

pillow_heif/tests/write_test.py

Lines 626 to 641 in 03c7beb

	@pytest.mark.skipif("svt" not in pillow_heif.libheif_info()["encoders"], reason="Requires SVT AVIF encoder.")
	@pytest.mark.skipif("aom" not in pillow_heif.libheif_info()["encoders"], reason="Requires AOM AVIF encoder.")
	def test_svt_encoder():
	im_rgb = helpers.gradient_rgb()
	buf_aom = BytesIO()
	im_rgb.save(buf_aom, format="AVIF")
	buf_svt = BytesIO()
	try:
	pillow_heif.options.PREFERRED_ENCODER["AVIF"] = "svt"
	im_rgb.save(buf_svt, format="AVIF")
	finally:
	pillow_heif.options.PREFERRED_ENCODER["AVIF"] = ""
	aom_img_data = Image.open(buf_aom).tobytes()
	svt_image_data = Image.open(buf_svt).tobytes()
	# print(f"AOM size: {len(aom_img_data)} , SVT size: {len(svt_image_data)}", )
	assert aom_img_data != svt_image_data # Suppose that: different decoders by default will have different results

for Pillow plugin alternative way to set option is to pass preferred_encoder as an argument to register_avif_opener or register_heif_opener

[MimoKar]

Ok. As it appears that I am dumb to compile it myself (spent a week on it before) is it possible to include the additional backends to the default package?

[bigcat88]

Unfortunately no, the package size can easily grow to 50+ MB for each wheel, and space on pypi is limited for each package.

If you are using Ubuntu, it is easy to install using PPA with libheif releases.
Another options is to create a discussion or issue in the libheif repository, and there will help you with building libheif with all these backends.

After that, building pillow-heif will be very easy, there should be no problems.

[MimoKar]

Don't plan to change backend to quicker one - SVT-AV1?

[MimoKar]

When I want to use a plugin system in libheif, where I need to put a DLL file for a specific codec that it will be used by pillow_heif?

[bigcat88]

if libehif is built with the PluginSystem enabled, than the value of this variable determines the directory from which load plugins:

https://github.com/strukturag/libheif/blob/2a764da6053f08b472f7127f8d95772e64ef015a/CMakeLists.txt#L78-L79

[MimoKar]

Is your libheif used in pillow-HEIF built with a plugin system? 
If not, it is possible to do it?

Plugin system is available on Linux only :-(

[MimoKar]

Ok, I was able to build libheif in mingw.
But now pillow_heif build is throwing this error:

Found 'heif.h' in 'D:\gitrepos\pillow_heif\libheif'
building '_pillow_heif' extension
b'T\x00h\x00e\x00 \x00s\x00y\x00n\x00t\x00a\x00x\x00 \x00o\x00f\x00 \x00t\x00h\x00e\x00 \x00c\x00o\x00m\x00m\x00a\x00n\x00d\x00 \x00i\x00s\x00 \x00i\x00n\x00c\x00o\x00r\x00r\x00e\x00c\x00t\x00.\x00\r\x00\n\x00'
error: Error executing cmd /u /c "C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvarsall.bat" x86_amd64 && set

[bigcat88]

it is the encoded in the unicode next message: "The syntax of the command is incorrect.\r\n"

but I have no clue what does it mean

[bigcat88]

I will think about bundling svt-a1 into next release, maybe I will.
Do you need it only on Windows?

[MimoKar]

Thanks.
I am using pillow_heif only on Windows now.

[bigcat88]

I asked here if it would be possible to use AVIF from pillow_heif if they merged the PR from pillow_avif_plugin, which would add AVIF support to Pillow itself:

python-pillow/Pillow#7983