Re: [Bino-list] Request for help: debug subtitle problem on ATI graphics cards

[Martin Lambers]

Hi Pedro!

On Fri, 1 Feb 2013 15:20:48 -0000, Pedro Silva Pinto wrote:
> Absolutely no problems playing the vídeo/subtitle on 1.4.2.
> Tried it on a i7 laptop with an ATI Mobility Radeon HD 4570, running
> Win7 x64. Second try on a i5 laptop with an ATI Mobility Radeon HD
> 3430, running Win7 x64. Smooth and stable.

Thanks for testing!

> However, I recommend Damir to try and select the subtitle stream
> before starting playback. I do have experienced some erratic behavior
> if the subtitles are activated in mid playback. For instance, while
> playing this video, selecting the subs made the video jump about 8
> seconds forward and the first subtitles were not displayed.
> Selecting the subtitles before hitting that play button, makes a
> difference.

Yes, the reason why subtitle switching during playback is problematic is
that afterwards all streams (video, audio, subtitles) need to find a
synchronization point where 1) all timestamps are exactly known and 2)
decoding can start from scratch (i.e. the next video frame must be a
key frame).

Depending on the encoding and container formats, this causes the
streams to "jump" a little - or in some cases, several seconds.

The same happens when switching audio tracks. There is no
straightforward way to solve this.

Regards,
Martin