On 22/02/2024 19:39, ChenLiucheng via ffmpeg-devel wrote:
On Feb 23, 2024, at 03:28, Mark Thompson <s...@jkqxz.net> wrote:
On 22/02/2024 18:46, gnattu via ffmpeg-devel wrote:
There is no device context to be setup, nor devices to be
selected with VideoToolbox. Just a simple return would allow
us to use derived device in filters like
`hwupload=derive_device=videotoolbox`
Signed-off-by: Gnattu OC <gnatt...@me.com>
---
libavutil/hwcontext_videotoolbox.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/libavutil/hwcontext_videotoolbox.c
b/libavutil/hwcontext_videotoolbox.c
index fe469dc161..d13199eca7 100644
--- a/libavutil/hwcontext_videotoolbox.c
+++ b/libavutil/hwcontext_videotoolbox.c
@@ -759,6 +759,14 @@ static int vt_device_create(AVHWDeviceContext *ctx, const
char *device,
return 0;
}
+static int vt_device_derive(AVHWDeviceContext *device_ctx,
+ AVHWDeviceContext *src_ctx, AVDictionary *opts,
+ int flags)
+{
+ // There is no context to be setup with VT, just return.
+ return 0;
+}
+
const HWContextType ff_hwcontext_type_videotoolbox = {
.type = AV_HWDEVICE_TYPE_VIDEOTOOLBOX,
.name = "videotoolbox",
@@ -766,6 +774,7 @@ const HWContextType ff_hwcontext_type_videotoolbox = {
.frames_priv_size = sizeof(VTFramesContext),
.device_create = vt_device_create,
+ .device_derive = vt_device_derive,
.frames_hwctx_size = sizeof(AVVTFramesContext),
.frames_init = vt_frames_init,
.frames_get_buffer = vt_get_buffer,
This derivation behaviour doesn't make any sense inside libavutil. Features
which are only for the ffmpeg utility should be implemented inside the ffmpeg
utility.
(Also, try -init_hw_device.)
> Well this does make sense.
>
> If only one type of hardware device is in use, then `-init_hw_device` will
suffice. However, if we use hardware filters with different device types, such as
OpenCL, and we want to switch to a VideoToolbox filter later in the chain, we will
have a issue. Since there is no `hwmap` between OpenCL and VideoToolbox, we need
to perform a `hwdownload` followed by a `hwupload`. If the `derive_device` option
cannot be used with `hwupload` due to `device_derive` not being implemented, the
filter will struggle to find the correct device for uploading. It may attempt to
upload to the OpenCL device without `device_derive` set if it comes after an
OpenCL filter.
>
Yes, it is unfortunate that the ffmpeg utility is missing this feature.
A libavfilter API user will set the correct hw_device_ctx on each filter and
your use-case will work properly, but the ffmpeg utility does not fully expose
the functionality of libavfilter to be able to do this.
This is mostly for syntax reasons; implementation would be straightforward. If
you can think of a good way to represent this in options to the ffmpeg utility
(which doesn't become too horrible with escaping) then I would very much
welcome suggestions.
Thanks,
- Mark
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