| Message ID | 20200721170007.4554-1-srinivas.kandagatla@linaro.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | ALSA: compress: add support to change codec profile in gapless playback | expand |
On Tue, 21 Jul 2020 19:00:01 +0200, Srinivas Kandagatla wrote: > > For gapless playback it is possible that each track can have different > codec profile with same decoder, for example we have WMA album, > we may have different tracks as WMA v9, WMA v10 and so on > Or if DSP's like QDSP have abililty to switch decoders on single stream > for each track, then this call could be used to set new codec parameters. > > Existing code does not allow to change this profile while doing gapless > playback. > > This patchset adds new SNDRV_COMPRESS_SET_CODEC_PARAMS IOCTL along with > flags in capablity structure to allow userspace to set this new > parameters required which switching codec profile, either for gapless > or cross fade usecase. One idea that came up at the previous audio conference regarding this implementation was to just allow SET_PARAMS during the stream is running (only if the driver sets the capability) instead of introducing yet a new ioctl and an ops. Would it make sense? I have no big objection to add a new ioctl if other people agree, though. thanks, Takashi
On 23-07-20, 14:38, Takashi Iwai wrote: > On Tue, 21 Jul 2020 19:00:01 +0200, > Srinivas Kandagatla wrote: > > > > For gapless playback it is possible that each track can have different > > codec profile with same decoder, for example we have WMA album, > > we may have different tracks as WMA v9, WMA v10 and so on > > Or if DSP's like QDSP have abililty to switch decoders on single stream > > for each track, then this call could be used to set new codec parameters. > > > > Existing code does not allow to change this profile while doing gapless > > playback. > > > > This patchset adds new SNDRV_COMPRESS_SET_CODEC_PARAMS IOCTL along with > > flags in capablity structure to allow userspace to set this new > > parameters required which switching codec profile, either for gapless > > or cross fade usecase. > > One idea that came up at the previous audio conference regarding this > implementation was to just allow SET_PARAMS during the stream is > running (only if the driver sets the capability) instead of > introducing yet a new ioctl and an ops. > Would it make sense? That does sound good but only issue would be that we need to somehow mark/document that buffer info is useless and would be discarded, how do we do that? > I have no big objection to add a new ioctl if other people agree, > though. > > > thanks, > > Takashi
On Thu, 23 Jul 2020 15:05:22 +0200, Vinod Koul wrote: > > On 23-07-20, 14:38, Takashi Iwai wrote: > > On Tue, 21 Jul 2020 19:00:01 +0200, > > Srinivas Kandagatla wrote: > > > > > > For gapless playback it is possible that each track can have different > > > codec profile with same decoder, for example we have WMA album, > > > we may have different tracks as WMA v9, WMA v10 and so on > > > Or if DSP's like QDSP have abililty to switch decoders on single stream > > > for each track, then this call could be used to set new codec parameters. > > > > > > Existing code does not allow to change this profile while doing gapless > > > playback. > > > > > > This patchset adds new SNDRV_COMPRESS_SET_CODEC_PARAMS IOCTL along with > > > flags in capablity structure to allow userspace to set this new > > > parameters required which switching codec profile, either for gapless > > > or cross fade usecase. > > > > One idea that came up at the previous audio conference regarding this > > implementation was to just allow SET_PARAMS during the stream is > > running (only if the driver sets the capability) instead of > > introducing yet a new ioctl and an ops. > > Would it make sense? > > That does sound good but only issue would be that we need to somehow > mark/document that buffer info is useless and would be discarded, how do > we do that? Yes, the buffer and no_wake_mode can be ignored in the gapless re-setup. Is your concern only about the documentation? Or something else needs to be changed significantly? It's a new scheme in anyway, so the documentation update is required... thanks, Takashi > > > I have no big objection to add a new ioctl if other people agree, > > though. > > > > > > thanks, > > > > Takashi > > -- > ~Vinod >
On 23-07-20, 15:17, Takashi Iwai wrote: > On Thu, 23 Jul 2020 15:05:22 +0200, > Vinod Koul wrote: > > > > On 23-07-20, 14:38, Takashi Iwai wrote: > > > On Tue, 21 Jul 2020 19:00:01 +0200, > > > Srinivas Kandagatla wrote: > > > > > > > > For gapless playback it is possible that each track can have different > > > > codec profile with same decoder, for example we have WMA album, > > > > we may have different tracks as WMA v9, WMA v10 and so on > > > > Or if DSP's like QDSP have abililty to switch decoders on single stream > > > > for each track, then this call could be used to set new codec parameters. > > > > > > > > Existing code does not allow to change this profile while doing gapless > > > > playback. > > > > > > > > This patchset adds new SNDRV_COMPRESS_SET_CODEC_PARAMS IOCTL along with > > > > flags in capablity structure to allow userspace to set this new > > > > parameters required which switching codec profile, either for gapless > > > > or cross fade usecase. > > > > > > One idea that came up at the previous audio conference regarding this > > > implementation was to just allow SET_PARAMS during the stream is > > > running (only if the driver sets the capability) instead of > > > introducing yet a new ioctl and an ops. > > > Would it make sense? > > > > That does sound good but only issue would be that we need to somehow > > mark/document that buffer info is useless and would be discarded, how do > > we do that? > > Yes, the buffer and no_wake_mode can be ignored in the gapless > re-setup. Is your concern only about the documentation? Or something > else needs to be changed significantly? It's a new scheme in anyway, > so the documentation update is required... My concern is potential abuse of API down the road, if you feel it is okay, I am okay with the proposal Thanks
On Thu, 23 Jul 2020 17:56:12 +0200, Vinod Koul wrote: > > On 23-07-20, 15:17, Takashi Iwai wrote: > > On Thu, 23 Jul 2020 15:05:22 +0200, > > Vinod Koul wrote: > > > > > > On 23-07-20, 14:38, Takashi Iwai wrote: > > > > On Tue, 21 Jul 2020 19:00:01 +0200, > > > > Srinivas Kandagatla wrote: > > > > > > > > > > For gapless playback it is possible that each track can have different > > > > > codec profile with same decoder, for example we have WMA album, > > > > > we may have different tracks as WMA v9, WMA v10 and so on > > > > > Or if DSP's like QDSP have abililty to switch decoders on single stream > > > > > for each track, then this call could be used to set new codec parameters. > > > > > > > > > > Existing code does not allow to change this profile while doing gapless > > > > > playback. > > > > > > > > > > This patchset adds new SNDRV_COMPRESS_SET_CODEC_PARAMS IOCTL along with > > > > > flags in capablity structure to allow userspace to set this new > > > > > parameters required which switching codec profile, either for gapless > > > > > or cross fade usecase. > > > > > > > > One idea that came up at the previous audio conference regarding this > > > > implementation was to just allow SET_PARAMS during the stream is > > > > running (only if the driver sets the capability) instead of > > > > introducing yet a new ioctl and an ops. > > > > Would it make sense? > > > > > > That does sound good but only issue would be that we need to somehow > > > mark/document that buffer info is useless and would be discarded, how do > > > we do that? > > > > Yes, the buffer and no_wake_mode can be ignored in the gapless > > re-setup. Is your concern only about the documentation? Or something > > else needs to be changed significantly? It's a new scheme in anyway, > > so the documentation update is required... > > My concern is potential abuse of API down the road, if you feel it is > okay, I am okay with the proposal If this can be potentially dangerous, it shouldn't be used, of course. What kind of scenario could it be? thanks, Takashi
On 23-07-20, 22:33, Takashi Iwai wrote: > On Thu, 23 Jul 2020 17:56:12 +0200, > Vinod Koul wrote: > > > > On 23-07-20, 15:17, Takashi Iwai wrote: > > > On Thu, 23 Jul 2020 15:05:22 +0200, > > > Vinod Koul wrote: > > > > > > > > On 23-07-20, 14:38, Takashi Iwai wrote: > > > > > On Tue, 21 Jul 2020 19:00:01 +0200, > > > > > Srinivas Kandagatla wrote: > > > > > > > > > > > > For gapless playback it is possible that each track can have different > > > > > > codec profile with same decoder, for example we have WMA album, > > > > > > we may have different tracks as WMA v9, WMA v10 and so on > > > > > > Or if DSP's like QDSP have abililty to switch decoders on single stream > > > > > > for each track, then this call could be used to set new codec parameters. > > > > > > > > > > > > Existing code does not allow to change this profile while doing gapless > > > > > > playback. > > > > > > > > > > > > This patchset adds new SNDRV_COMPRESS_SET_CODEC_PARAMS IOCTL along with > > > > > > flags in capablity structure to allow userspace to set this new > > > > > > parameters required which switching codec profile, either for gapless > > > > > > or cross fade usecase. > > > > > > > > > > One idea that came up at the previous audio conference regarding this > > > > > implementation was to just allow SET_PARAMS during the stream is > > > > > running (only if the driver sets the capability) instead of > > > > > introducing yet a new ioctl and an ops. > > > > > Would it make sense? > > > > > > > > That does sound good but only issue would be that we need to somehow > > > > mark/document that buffer info is useless and would be discarded, how do > > > > we do that? > > > > > > Yes, the buffer and no_wake_mode can be ignored in the gapless > > > re-setup. Is your concern only about the documentation? Or something > > > else needs to be changed significantly? It's a new scheme in anyway, > > > so the documentation update is required... > > > > My concern is potential abuse of API down the road, if you feel it is > > okay, I am okay with the proposal > > If this can be potentially dangerous, it shouldn't be used, of course. > What kind of scenario could it be? I can think of users trying to invoke this incorrectly, right now we would reject this. Maybe, we can add checks like, if next_track is set and then copy the codec params only to prevent any misuse. Do you think that would be okay?
On Thu, 06 Aug 2020 13:08:13 +0200, Vinod Koul wrote: > > On 23-07-20, 22:33, Takashi Iwai wrote: > > On Thu, 23 Jul 2020 17:56:12 +0200, > > Vinod Koul wrote: > > > > > > On 23-07-20, 15:17, Takashi Iwai wrote: > > > > On Thu, 23 Jul 2020 15:05:22 +0200, > > > > Vinod Koul wrote: > > > > > > > > > > On 23-07-20, 14:38, Takashi Iwai wrote: > > > > > > On Tue, 21 Jul 2020 19:00:01 +0200, > > > > > > Srinivas Kandagatla wrote: > > > > > > > > > > > > > > For gapless playback it is possible that each track can have different > > > > > > > codec profile with same decoder, for example we have WMA album, > > > > > > > we may have different tracks as WMA v9, WMA v10 and so on > > > > > > > Or if DSP's like QDSP have abililty to switch decoders on single stream > > > > > > > for each track, then this call could be used to set new codec parameters. > > > > > > > > > > > > > > Existing code does not allow to change this profile while doing gapless > > > > > > > playback. > > > > > > > > > > > > > > This patchset adds new SNDRV_COMPRESS_SET_CODEC_PARAMS IOCTL along with > > > > > > > flags in capablity structure to allow userspace to set this new > > > > > > > parameters required which switching codec profile, either for gapless > > > > > > > or cross fade usecase. > > > > > > > > > > > > One idea that came up at the previous audio conference regarding this > > > > > > implementation was to just allow SET_PARAMS during the stream is > > > > > > running (only if the driver sets the capability) instead of > > > > > > introducing yet a new ioctl and an ops. > > > > > > Would it make sense? > > > > > > > > > > That does sound good but only issue would be that we need to somehow > > > > > mark/document that buffer info is useless and would be discarded, how do > > > > > we do that? > > > > > > > > Yes, the buffer and no_wake_mode can be ignored in the gapless > > > > re-setup. Is your concern only about the documentation? Or something > > > > else needs to be changed significantly? It's a new scheme in anyway, > > > > so the documentation update is required... > > > > > > My concern is potential abuse of API down the road, if you feel it is > > > okay, I am okay with the proposal > > > > If this can be potentially dangerous, it shouldn't be used, of course. > > What kind of scenario could it be? > > I can think of users trying to invoke this incorrectly, right now we > would reject this. > > Maybe, we can add checks like, if next_track is set and then copy the > codec params only to prevent any misuse. > > Do you think that would be okay? Yes, it's the same condition check that was proposed for the new ioctl. Takashi