On Mon, 23.02.09 08:45, Takashi Iwai (tiwai@xxxxxxx) wrote: > > At Sun, 22 Feb 2009 00:45:04 +0100, > Lennart Poettering wrote: > > > > On Tue, 07.10.08 17:32, Takashi Iwai (tiwai@xxxxxxx) wrote: > > > > > Hi, > > > > Sorry for the overly long delay. > > > > > > the patch below (to the latest sound git tree) adds the extra delay > > > count for USB-audio driver. This change will appear as the return > > > value of snd_pcm_delay(). > > > > > > Could you check whether it's appropriate behavior you've wanted? > > > > I have now tested this patch on the current 2.6.29-rc5 kernel. The > > effect is that snd_pcm_delay() returns always increasing values, as if > > the playback never proceeds. Most movie players which need that call > > to synchronize video frames hence stall completely. > > OK, that's bad. However, the increased value of snd_pcm_delay() is > exactly the effect. The usb-audio always prefetch the buffer in > advance. > > That means, changing (or "fixing") snd_pcm_delay() would cause many > regressions with many apps -- thus basically we are not allowed to > change the semantics any more at this too late point. > > I feel it's better to introduce another kernel-side API to give a > better sync/timing information, and mark snd_pcm_delay as obsolete for > future (although we can never deprecate such a basic API). No, snd_pcm_delay() with this patch is clearly broken: it apparently increases at the same speed as the hw ptr, ignoring the app ptr. i.e. after 5 min of playback the delay will be reported a 5 mins! After 10 min of playback the delay will be reported as 10 mins! This is *not* a simple incompatibility with mplayer. The patch is borked. This has nothing to do with changing semantics and creating incompatibilities. Lennart -- Lennart Poettering Red Hat, Inc. lennart [at] poettering [dot] net ICQ# 11060553 http://0pointer.net/lennart/ GnuPG 0x1A015CC4 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
