[FFmpeg-devel] [WIP][PATCH 0/4] Encoding API code restructuration

[James Almer]

On 2/27/2020 3:45 PM, Carl Eugen Hoyos wrote:
> Am Do., 27. Feb. 2020 um 19:32 Uhr schrieb James Almer <jamrial at gmail.com>:
>>
>> On 2/27/2020 3:22 PM, Carl Eugen Hoyos wrote:
>>> Am Do., 27. Feb. 2020 um 19:11 Uhr schrieb James Almer <jamrial at gmail.com>:
>>>>
>>>> This set follows the same logic as 061a0c14bb, but for the encode API: The
>>>> new public API will no longer be a wrapper around the old deprecated one, and
>>>> the internal API used by the encoders now consists of a single receive_packet()
>>>> callback that pulls frames as required.
>>>>
>>>> Because of the above, PATCH 2/4 can't be applied until all the relevant encoders
>>>> have been adapted, and said changes squashed into it. This means librav1e, nvenc,
>>>> amfenc, v4l2_m2m, and vaapi_enc.
>>>> I have ported librav1e both to test this set and for it to work as an example
>>>> for the maintainers of the other three encoders in order to get an idea of what
>>>> they should do.
>>>
>>> How does performance change with these patches?
>>
>> I didn't notice any performance hit.
> 
> I had hoped for a performance gain...
> 
> Sorry for asking: Did you test? They are rumours we once upon a time
> changed something in libavcodec which had a huge speed impact that
> was simply ignored here...

I did with librav1e which uses the new API callback internally, but i
just tried quickly again using mpeg2video which uses the old API
callback internally just to confirm:
./ffmpeg -framerate 24 -i ~/ToS/00%3d.png -pix_fmt yuv420p -benchmark
-c:v mpeg2video -f null -t 10 -

Before
frame=  240 fps= 88 q=31.0 Lsize=N/A time=00:00:09.95 bitrate=N/A
speed=3.65x
video:1822kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: unknown
bench: utime=9.922s stime=0.312s rtime=2.745s
bench: maxrss=97532kB

After
frame=  240 fps= 88 q=31.0 Lsize=N/A time=00:00:09.95 bitrate=N/A
speed=3.64x
video:1822kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: unknown
bench: utime=9.656s stime=0.453s rtime=2.761s
bench: maxrss=93892kB

> 
>>> Am I correct that this changes the "new" api which so many
>>> users complained about?
>>
>> I'm not sure what users complained about, but this doesn't change the
>> public API as far as library users are concerned. It changes how it
>> works internally, removing the dependency it had on the old deprecated API.
> 
> Thank you for the explanation!
> 
> Carl Eugen
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>