[FFmpeg-user] overlay_qsv with hardware decode and encode

[Vladimir Mishonov]

On 2025-02-28 23:26, BloodMan wrote:
> Hi Vladimir,
> 
> W dniu 2025-02-28 o 20:21, Vladimir Mishonov via ffmpeg-user pisze:
>> ffmpeg \
>>   -hwaccel vaapi -hwaccel_output_format vaapi -i 
>> rtmp://localhost/stream1 \
>>   -hwaccel vaapi -hwaccel_output_format vaapi -i 
>> rtmp://localhost/stream2 \
>>   -filter_complex "[0:v][1:v]overlay_vaapi=w=500" \
>>   -c:v h264_vaapi -global_quality 25 -g 50 -r 25 -an -f null -
>> 
>> And no, putting "scale_vaapi" before overlay here does not help.
> 
> I see on previous posts that resolutions are different, but also frame 
> rates are different and colour spaces (bt709 vs "") are different.
> 
> Are you really sure the problem is the resolution?
> (I have no way to check, I'm just thinking out)

It is possible, but needs furher testing to say for sure.

1) The FPS is likely not the problem, as the overlay filter uses the FPS 
of the first input and either drops or duplicates frames of the second 
one to match.

2) As for the colorspace, I'm not certain. I suppose it may be a 
hardware limitation that when the hardware decoder is initialized, it 
can only work with one colorspace at a time. But in this case, the 
produced error message must be quite misleading.

I have only two kinds of live-streaming sources available at the moment 
(the same that were demonstrated in the logs earlier). When any number 
of them is used as inputs, hardware decoding works only when all sources 
are of the same kind. But software decoding works with any combination 
of them.

However, I think I have a couple of unused cameras lying around; they 
are of the same model so anything like the FPS, colorspace etc. must 
match, but I could try setting a different resolution on the second one 
and see if it works. It probably won't, but I will of course report back 
if it does.

--
Kind regards,
Vladimir

> 
> --
> BloodMan
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