On 10/10/2023 8:54 AM, Anton Khirnov wrote:
Quoting James Almer (2023-10-10 13:44:19)
On 10/10/2023 8:17 AM, Anton Khirnov wrote:
Quoting James Almer (2023-10-07 18:24:56)
This is a simple set to add support to stream wide, container level cropping
parameters, as featured in formats like Matroska and ISOBMFF. It's needed for
things like AV1 streams generated by certain hardware encoders that produce
dimension aligned output, and unlike H26x, can't export cropping info within
the bitstream.
In this set i add the packet side data type, mux and demux support to Matroska,
and handling code to ffmpeg and ffplay. Missing is support for clap boxes in
ISOBMFF, and exporting the relevant side data from encoders like AMF.
It's a rebased and updated version to the set i sent a month ago.
Why is there no lavc-decoder handling? I would expect cropping side data
submitted to lavc to be somehow propagated to decoded frames.
Though there is a question of how to combine side data with the
codec-level cropping.
I thought about adding lavc support alongside the CLI handling, yeah.
And it should be a matter of adding the values to the existing ones in
frame->crop_* as exported by decoders, which av_frame_apply_cropping()
will then handle.
And the reason i add support to the CLI by including a filter instead of
leaving it up to lavc is that av_frame_apply_cropping() may not do exact
cropping if AV_CODEC_FLAG_UNALIGNED is not set.
I intend to have the CLI always set AVCodecContext.apply_cropping=0 and
have it handled by lavfi for this exact reason, just didn't get to
actually doing it yet. Feel free and welcome to do it yourself.
The cropping filter doesn't look at the frame cropping fields, though.
It in fact exports cropping into them if you pass it hw frames. It only
looks at input arguments. So it doesn't seem like that can be done
without changing the filter.
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