[vlc-devel] [PATCH 2/3] video_output: create pictures with the display format with interactive filters

[Steve Lhomme]

On 2020-08-13 16:47, Rémi Denis-Courmont wrote:
> Le torstaina 13. elokuuta 2020, 15.13.06 EEST Steve Lhomme a écrit :
>> Also used for whatever the last filter of the filter chains is.
>> ---
>>   src/video_output/video_output.c | 12 +++++++-----
>>   1 file changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/src/video_output/video_output.c
>> b/src/video_output/video_output.c index 6097b9df7f9..dc636d72928 100644
>> --- a/src/video_output/video_output.c
>> +++ b/src/video_output/video_output.c
>> @@ -859,12 +859,14 @@ static void
>> ThreadDelAllFilterCallbacks(vout_thread_sys_t *vout) static picture_t
>> *VoutVideoFilterInteractiveNewPicture(filter_t *filter) {
>>       vout_thread_sys_t *sys = filter->owner.sys;
>> +    picture_t *picture;
>>
>> -    picture_t *picture = picture_pool_Get(sys->private.private_pool);
>> -    if (picture) {
>> -        picture_Reset(picture);
>> -        video_format_CopyCropAr(&picture->format, &filter->fmt_out.video);
>> -    }
>> +    vlc_mutex_lock(&sys->display_lock);
>> +    if (sys->display)
>> +        picture =  picture_NewFromFormat(&sys->display->fmt);
>> +    else
>> +        picture = NULL;
>> +    vlc_mutex_unlock(&sys->display_lock);
>>       return picture;
>>   }
> 
> Are you sure that we can safely lock the display from that callback?

The filter chain(s) is only allocating pictures when calling 
filter_chain_VideoFilter(). This happens in 
ThreadDisplayPreparePicture() in the vout thread.

ThreadDisplayRenderPicture() called right after also holds the same lock 
for most of its duration. With a notable difference, the filters.lock is 
not held in this case. ThreadProcessMouseState() also holds them separately.

It doesn't seem that the code can mix them together as of now. But it 
may not be clean to allow this. It's probably cleaner to use 
filter_chain_GetFmtOut() instead to the get the proper video_format_t to 
use.