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audio: make recording packet length calculation exact

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Introduce the new function st_rate_frames_out() to calculate the
exact number of audio output frames the resampling code can
generate from a given number of audio input frames. When upsampling,
this function returns the maximum number of output frames.

This new function replaces the audio_frontend_frames_in()
function, which calculated the average number of output frames
rounded down to the nearest integer. The audio_frontend_frames_in()
function was additionally used to limit the number of output frames
to the resample buffer size. In audio_pcm_sw_read() the variable
resample_buf.size replaces the open coded audio_frontend_frames_in()
function. In audio_run_in() an additional MIN() function is
necessary.

After this patch the audio packet length calculation for audio
recording is exact.

Acked-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-Id: <20230224190555.7409-12-vr_qemu@t-online.de>
This commit is contained in:
Volker Rümelin 2023-02-24 20:05:52 +01:00 committed by Marc-André Lureau
parent fbde1edf06
commit a9ea567873
3 changed files with 50 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
audio/audio.c
View File

@ -579,7 +579,7 @@ static void audio_pcm_sw_resample_in(SWVoiceIn *sw,
static size_t audio_pcm_sw_read(SWVoiceIn *sw, void *buf, size_t buf_len)
{
HWVoiceIn *hw = sw->hw;
size_t live, frames_out_max, swlim, total_in, total_out;
size_t live, frames_out_max, total_in, total_out;
live = hw->total_samples_captured - sw->total_hw_samples_acquired;
if (!live) {
@ -590,12 +590,10 @@ static size_t audio_pcm_sw_read(SWVoiceIn *sw, void *buf, size_t buf_len)
return 0;
}
frames_out_max = buf_len / sw->info.bytes_per_frame;
frames_out_max = MIN(buf_len / sw->info.bytes_per_frame,
sw->resample_buf.size);
swlim = (live * sw->ratio) >> 32;
swlim = MIN(swlim, frames_out_max);
audio_pcm_sw_resample_in(sw, live, swlim, &total_in, &total_out);
audio_pcm_sw_resample_in(sw, live, frames_out_max, &total_in, &total_out);
if (!hw->pcm_ops->volume_in) {
mixeng_volume(sw->resample_buf.buffer, total_out, &sw->vol);
@ -979,18 +977,6 @@ void AUD_set_active_in (SWVoiceIn *sw, int on)
}
}
/**
* audio_frontend_frames_in() - returns the number of frames the resampling
* code generates from frames_in frames
*
* @sw: audio recording frontend
* @frames_in: number of frames
*/
static size_t audio_frontend_frames_in(SWVoiceIn *sw, size_t frames_in)
{
return (int64_t)frames_in * sw->ratio >> 32;
}
static size_t audio_get_avail (SWVoiceIn *sw)
{
size_t live;
@ -1007,9 +993,9 @@ static size_t audio_get_avail (SWVoiceIn *sw)
}
ldebug (
"%s: get_avail live %zu frontend frames %zu\n",
"%s: get_avail live %zu frontend frames %u\n",
SW_NAME (sw),
live, audio_frontend_frames_in(sw, live)
live, st_rate_frames_out(sw->rate, live)
);
return live;
@ -1314,8 +1300,9 @@ static void audio_run_in (AudioState *s)
size_t sw_avail = audio_get_avail(sw);
size_t avail;
avail = audio_frontend_frames_in(sw, sw_avail);
avail = st_rate_frames_out(sw->rate, sw_avail);
if (avail > 0) {
avail = MIN(avail, sw->resample_buf.size);
sw->callback.fn(sw->callback.opaque,
avail * sw->info.bytes_per_frame);
}

41
audio/mixeng.c
View File

@ -440,6 +440,47 @@ void st_rate_stop (void *opaque)
g_free (opaque);
}
/**
* st_rate_frames_out() - returns the number of frames the resampling code
* generates from frames_in frames
*
* @opaque: pointer to struct rate
* @frames_in: number of frames
*
* When upsampling, there may be more than one correct result. In this case,
* the function returns the maximum number of output frames the resampling
* code can generate.
*/
uint32_t st_rate_frames_out(void *opaque, uint32_t frames_in)
{
struct rate *rate = opaque;
uint64_t opos_end, opos_delta;
uint32_t ipos_end;
uint32_t frames_out;
if (rate->opos_inc == 1ULL << 32) {
return frames_in;
}
/* no output frame without at least one input frame */
if (!frames_in) {
return 0;
}
/* last frame read was at rate->ipos - 1 */
ipos_end = rate->ipos - 1 + frames_in;
opos_end = (uint64_t)ipos_end << 32;
/* last frame written was at rate->opos - rate->opos_inc */
if (opos_end + rate->opos_inc <= rate->opos) {
return 0;
}
opos_delta = opos_end - rate->opos + rate->opos_inc;
frames_out = opos_delta / rate->opos_inc;
return opos_delta % rate->opos_inc ? frames_out : frames_out - 1;
}
/**
* st_rate_frames_in() - returns the number of frames needed to
* get frames_out frames after resampling

1
audio/mixeng.h
View File

@ -52,6 +52,7 @@ void st_rate_flow(void *opaque, st_sample *ibuf, st_sample *obuf,
void st_rate_flow_mix(void *opaque, st_sample *ibuf, st_sample *obuf,
size_t *isamp, size_t *osamp);
void st_rate_stop (void *opaque);
uint32_t st_rate_frames_out(void *opaque, uint32_t frames_in);
uint32_t st_rate_frames_in(void *opaque, uint32_t frames_out);
void mixeng_clear (struct st_sample *buf, int len);
void mixeng_volume (struct st_sample *buf, int len, struct mixeng_volume *vol);