[vlc-devel] [PATCH] transcode: Correctly reset video drift

[Aurélien Nephtali]

On Fri, Jun 8, 2012 at 9:59 AM, Aurélien Nephtali
<aurelien.nephtali at gmail.com> wrote:
> On Thu, Jun 7, 2012 at 8:57 PM, Laurent Aimar <fenrir at elivagar.org> wrote:
>> On Thu, Jun 07, 2012 at 05:43:50PM +0200, Aurélien Nephtali wrote:
>>> Hi,
>>>
>>> On Thu, Jun 7, 2012 at 5:29 PM, Hugo Beauzée-Luyssen <hugo at beauzee.fr> wrote:
>>> > On Thu, Jun 7, 2012 at 4:55 PM, Aurélien Nephtali
>>> > <aurelien.nephtali at gmail.com> wrote:
>>> >> Hi,
>>> >>
>>> >> See attached patch.
>>> >>
>>> >> Thanks.
>>> >>
>>> >> --
>>> >> Aurélien Nephtali
>>> >
>>> > Hello,
>>> >
>>> > Please use spaces instead of tabs.
>>> Fixed, sorry about that.
>>
>> I think your patch is incomplete to fully fix the issue.
>> The code is:
>>
>>>     if( p_sys->b_master_sync )
>>>     {
>>>         mtime_t i_pts = date_Get( &id->interpolated_pts ) + 1;
>>>         if (unlikely ( p_pic->date - i_pts > MASTER_SYNC_MAX_DRIFT
>>>               || p_pic->date - i_pts < -MASTER_SYNC_MAX_DRIFT ) )
>>>         {
>>>             msg_Dbg( p_stream, "drift is too high, resetting master sync" );
>>>             date_Set( &id->interpolated_pts, p_pic->date );
>>>             i_pts = p_pic->date + 1;
>> I don't understand the need of this line (after the comment below).
>>>         }
>>>         date_Increment( &id->interpolated_pts, 1 );
>> I think i_pts should be set to the result of the increment.
>>>
>>>         if( unlikely( b_need_duplicate ) )
>>>         {
>> [Here your patch add a missing date_Increment() ]
>>>            if( p_sys->i_threads >= 1 )
>>>            {
>>>                /* We can't modify the picture, we need to duplicate it */
>>>                p_pic2 = video_new_buffer_decoder( id->p_decoder );
>>>                if( likely( p_pic2 != NULL ) )
>>>                {
>>>                    picture_Copy( p_pic2, p_pic );
>>>                    p_pic2->date = i_pts;
>>>                }
>>>            }
>>>            else
>>>            {
>>>                block_t *p_block;
>>>                p_pic->date = i_pts;
>>>                p_block = id->p_encoder->pf_encode_video(id->p_encoder, p_pic);
>>>                block_ChainAppend( out, p_block );
>>>            }
>>>        }
>>>     }
>>
>> Could you recheck against your test cases?
>>
>
> With my patch and your suggestion it still works.
> I will test this with more streams to see if it is OK.
>

In fact, the result is not good at all. The video is not smooth even
with a clean stream.
My first test was wrong (I just tested quality).

You can see the results here :
    - http://86.65.94.103/ok.ts (only my patch)
    - http://86.65.94.103/ko.ts (my patch + your suggestion)

This is the dump that makes vlc-git duplicates each frame on a
particular glitch (during the Jeep ad) but this time the "not smooth"
effect is visible since the start of the encoding.

-- 
Aurélien Nephtali