[FFmpeg-devel] scaling option

[Dennis Mungai]

On Tue, 26 Mar 2019 at 18:21, Yufei He <yhe at matrox.com> wrote:

> On 03/26/2019 08:53 AM, Timo Rothenpieler wrote:
> On 26/03/2019 13:47, Yufei He wrote:
> Hi
>
> Is there option for scaling on transcoding ?
>
> e.g. transcoding from a quadhd file to 640 * 480.
>
> Thanks.
>
> Yufei.
>
>
> Yes there is, but this is ffmpeg-devel, so not the place to ask user
> questions.
>
> Yes, I see the option of -vf scale=width:height
> We can do scaling on decoding or encoding, my question was to check if
> there is scaling option for codec.
> I'll add special scaling option to our codec.
>
>
Hello there,

Scaling comes in two forms (correct me if I'm wrong):

1. Specific video filters, such as the scale filters, and other
hardware-accelerated implementations, such as scale_npp, scale_cuda,
scale_vaapi, etc.
2. Decoders (Not too sure if equating the private -resize option provided
by these decoders is equivalent to "scaling"):

See the example provided by the likes of the cuvid implementations, such as
h264_cuvid, etc:

ffmpeg -h decoder=h264_cuvid

The -resize option therein acts as a scaler.

Are you planning to implement a codec-specific hardware (or software-based)
scaler (implemented as a video filter or a decoder), with similar
functionality?