At Sun, 25 Nov 2007 22:12:26 +0100, Lennart Poettering wrote: > > Hi! > > Please consider merging this patch we ship in Fedora: > > http://cvs.fedoraproject.org/viewcvs/*checkout*/devel/alsa-plugins/1.0.14-state-xrun.patch?rev=1.1 > > It adds support to report back XRUN to the application if one > happens. This is required to make some applications work on top of the > pulse plugin. One being XMMS, which checks if a song finished to play > by waiting for an XRUN (yes, I don't argue that XMMS shouldn't do > that, but nonetheless it is a good thing if XRUNs are reported > properly.) > > Now, this patch is a bit problematic, since it touches pcm->io.state > which is not supposed to be touched by ioplug-based plugins -- > according to the comments in ioplug. However, I saw no other way to > fix this, and from judging the ioplug code overwriting the variable > should be safe. Thus I decided to simply touch the variable but > documented it in a comment. > > Alternatively, ioplug could be beefed up to properly handle XRUNs, but > I thought this fix is simpler. But it's a layer violation :) We need a proper state-notification function. It'd be simply setting the state in the end, but at least, it's clear and the ioplug can do any action or sanity-check if once needed. A proposed patch is below. Comments? Takashi diff -r 672c5387645d include/pcm_ioplug.h --- a/include/pcm_ioplug.h Fri Nov 23 15:46:48 2007 +0100 +++ b/include/pcm_ioplug.h Mon Nov 26 11:32:10 2007 +0100 @@ -208,6 +208,9 @@ int snd_pcm_ioplug_set_param_minmax(snd_ int snd_pcm_ioplug_set_param_minmax(snd_pcm_ioplug_t *io, int type, unsigned int min, unsigned int max); int snd_pcm_ioplug_set_param_list(snd_pcm_ioplug_t *io, int type, unsigned int num_list, const unsigned int *list); +/* change PCM status */ +int snd_pcm_ioplug_set_state(snd_pcm_ioplug_t *ioplug, snd_pcm_state_t state); + /** \} */ #endif /* __ALSA_PCM_IOPLUG_H */ diff -r 672c5387645d src/pcm/pcm_ioplug.c --- a/src/pcm/pcm_ioplug.c Fri Nov 23 15:46:48 2007 +0100 +++ b/src/pcm/pcm_ioplug.c Mon Nov 26 11:32:10 2007 +0100 @@ -614,6 +614,8 @@ static snd_pcm_sframes_t snd_pcm_ioplug_ snd_pcm_uframes_t avail; snd_pcm_ioplug_hw_ptr_update(pcm); + if (io->data->state == SNDRV_PCM_STATE_XRUN) + return -EPIPE; if (pcm->stream == SND_PCM_STREAM_CAPTURE && pcm->access != SND_PCM_ACCESS_RW_INTERLEAVED && pcm->access != SND_PCM_ACCESS_RW_NONINTERLEAVED) { @@ -1037,3 +1039,19 @@ const snd_pcm_channel_area_t *snd_pcm_io return snd_pcm_mmap_areas(ioplug->pcm); return NULL; } + +/** + * \brief Change the ioplug PCM status + * \param ioplug the ioplug handle + * \param state the PCM status + * \return zero if successful or a negative error code + * + * Changes the PCM status of the ioplug to the given value. + * This function can be used for external plugins to notify the status + * change, e.g. XRUN. + */ +int snd_pcm_ioplug_set_state(snd_pcm_ioplug_t *ioplug, snd_pcm_state_t state) +{ + ioplug->state = state; + return 0; +} _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
