From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
To: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Takashi Iwai <tiwai@suse.de>,
Vinod Koul <vinod.koul@linux.intel.com>,
Richard Fitzgerald <rf@opensource.wolfsonmicro.com>,
alsa-devel@alsa-project.org
Subject: Re: [PATCH] ALSA: core: don't return uninitialized snd_compr_tstamp
Date: Mon, 04 Feb 2013 08:23:14 -0600 [thread overview]
Message-ID: <510FC452.1070906@linux.intel.com> (raw)
In-Reply-To: <1359599832-6210-1-git-send-email-broonie@opensource.wolfsonmicro.com>
> The snd_compr_update_tstamp() can only fill in the snd_compr_tstamp
> if the codec implements the pointer() function. If that happened
> the code was previously returning uninitialized garbage in the
> tstamp because it wasn't initialized anywhere.
>
> This change zero-fills the tstamp in the two places it is used
> before calling snd_compr_update_tstamp(), and also has
> snd_compr_update_tstamp() return an error indication if it
> can't provide a tstamp. For the case of snd_compr_calc_avail()
> it ignores this error because we still need to return info on
> the available buffer space even if we can't provide tstamp
> info - when the tstamp is not valid all fields are now
> guaranteed to be zero.
I think I am missing something here. For compressed data, the DSP really
needs to return a timestamp or the application will not be able to track
the audio time, it'll only be able to refill buffers. Since with
variable-rate compression we cannot translate bytes to time, isn't it a
requirement that timestamps be supported for this API? If you don't
support the .pointer, how will you provide this information to
user-space levels?
Thanks,
-Pierre
next prev parent reply other threads:[~2013-02-04 14:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-31 2:37 [PATCH] ALSA: core: don't return uninitialized snd_compr_tstamp Mark Brown
2013-01-31 2:53 ` Vinod Koul
2013-02-04 14:23 ` Pierre-Louis Bossart [this message]
2013-02-04 14:43 ` Takashi Iwai
-- strict thread matches above, loose matches on Subject: below --
2013-02-11 13:44 Mark Brown
2013-02-11 14:05 ` Takashi Iwai
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