[FFmpeg-devel] scaling option

Yufei He yhe at matrox.com
Tue Mar 26 20:20:44 EET 2019


On 03/26/2019 11:31 AM, Dennis Mungai wrote:
> 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?
Hi Dennis
Our hardware m264 supports scaling and encoding or decoding at the same 
time, this saves memory copy time between host and card if it's scaled 
in host or in other separate filter.
I'm trying to make it work in FFmpeg.

Yufei.
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