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[PATCH v3 13/15] audio: handle leftover audio frame from upsampling
From: |
Volker Rümelin |
Subject: |
[PATCH v3 13/15] audio: handle leftover audio frame from upsampling |
Date: |
Fri, 24 Feb 2023 20:05:53 +0100 |
Upsampling may leave one remaining audio frame in the input
buffer. The emulated audio playback devices are currently
resposible to write this audio frame again in the next write
cycle. Push that task down to audio_pcm_sw_write.
This is another step towards an audio callback interface that
guarantees that when audio frontends are told they can write
n audio frames, they can actually do so.
Acked-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
---
audio/audio.c | 34 ++++++++++++++++++++++++++++------
audio/audio_template.h | 6 ++++++
2 files changed, 34 insertions(+), 6 deletions(-)
diff --git a/audio/audio.c b/audio/audio.c
index dad17e59b8..4836ab8ca8 100644
--- a/audio/audio.c
+++ b/audio/audio.c
@@ -731,16 +731,21 @@ static size_t audio_pcm_sw_write(SWVoiceOut *sw, void
*buf, size_t buf_len)
hw_free = hw_free > live ? hw_free - live : 0;
frames_out_max = MIN(dead, hw_free);
sw_max = st_rate_frames_in(sw->rate, frames_out_max);
- fe_max = MIN(buf_len / sw->info.bytes_per_frame, sw->resample_buf.size);
+ fe_max = MIN(buf_len / sw->info.bytes_per_frame + sw->resample_buf.pos,
+ sw->resample_buf.size);
frames_in_max = MIN(sw_max, fe_max);
if (!frames_in_max) {
return 0;
}
- sw->conv(sw->resample_buf.buffer, buf, frames_in_max);
- if (!sw->hw->pcm_ops->volume_out) {
- mixeng_volume(sw->resample_buf.buffer, frames_in_max, &sw->vol);
+ if (frames_in_max > sw->resample_buf.pos) {
+ sw->conv(sw->resample_buf.buffer + sw->resample_buf.pos,
+ buf, frames_in_max - sw->resample_buf.pos);
+ if (!sw->hw->pcm_ops->volume_out) {
+ mixeng_volume(sw->resample_buf.buffer + sw->resample_buf.pos,
+ frames_in_max - sw->resample_buf.pos, &sw->vol);
+ }
}
audio_pcm_sw_resample_out(sw, frames_in_max, frames_out_max,
@@ -749,6 +754,22 @@ static size_t audio_pcm_sw_write(SWVoiceOut *sw, void
*buf, size_t buf_len)
sw->total_hw_samples_mixed += total_out;
sw->empty = sw->total_hw_samples_mixed == 0;
+ /*
+ * Upsampling may leave one audio frame in the resample buffer. Decrement
+ * total_in by one if there was a leftover frame from the previous resample
+ * pass in the resample buffer. Increment total_in by one if the current
+ * resample pass left one frame in the resample buffer.
+ */
+ if (frames_in_max - total_in == 1) {
+ /* copy one leftover audio frame to the beginning of the buffer */
+ *sw->resample_buf.buffer = *(sw->resample_buf.buffer + total_in);
+ total_in += 1 - sw->resample_buf.pos;
+ sw->resample_buf.pos = 1;
+ } else if (total_in >= sw->resample_buf.pos) {
+ total_in -= sw->resample_buf.pos;
+ sw->resample_buf.pos = 0;
+ }
+
#ifdef DEBUG_OUT
dolog (
"%s: write size %zu written %zu total mixed %zu\n",
@@ -1155,8 +1176,9 @@ static void audio_run_out (AudioState *s)
} else {
free = 0;
}
- if (free > 0) {
- free = MIN(free, sw->resample_buf.size);
+ if (free > sw->resample_buf.pos) {
+ free = MIN(free, sw->resample_buf.size)
+ - sw->resample_buf.pos;
sw->callback.fn(sw->callback.opaque,
free * sw->info.bytes_per_frame);
}
diff --git a/audio/audio_template.h b/audio/audio_template.h
index a0b653f52c..0d8aab6fad 100644
--- a/audio/audio_template.h
+++ b/audio/audio_template.h
@@ -138,6 +138,12 @@ static int glue (audio_pcm_sw_alloc_resources_, TYPE) (SW
*sw)
return -1;
}
+ /*
+ * Allocate one additional audio frame that is needed for upsampling
+ * if the resample buffer size is small. For large buffer sizes take
+ * care of overflows.
+ */
+ samples = samples < INT_MAX ? samples + 1 : INT_MAX;
sw->resample_buf.buffer = g_new0(st_sample, samples);
sw->resample_buf.size = samples;
sw->resample_buf.pos = 0;
--
2.35.3
- [PATCH v3 01/15] audio: change type of mix_buf and conv_buf, (continued)
- [PATCH v3 01/15] audio: change type of mix_buf and conv_buf, Volker Rümelin, 2023/02/24
- [PATCH v3 03/15] audio: make the resampling code greedy, Volker Rümelin, 2023/02/24
- [PATCH v3 04/15] audio: replace the resampling loop in audio_pcm_sw_write(), Volker Rümelin, 2023/02/24
- [PATCH v3 05/15] audio: remove sw == NULL check, Volker Rümelin, 2023/02/24
- [PATCH v3 07/15] audio: don't misuse audio_pcm_sw_write(), Volker Rümelin, 2023/02/24
- [PATCH v3 08/15] audio: remove unused noop_conv() function, Volker Rümelin, 2023/02/24
- [PATCH v3 09/15] audio: make playback packet length calculation exact, Volker Rümelin, 2023/02/24
- [PATCH v3 10/15] audio: replace the resampling loop in audio_pcm_sw_read(), Volker Rümelin, 2023/02/24
- [PATCH v3 11/15] audio: rename variables in audio_pcm_sw_read(), Volker Rümelin, 2023/02/24
- [PATCH v3 06/15] audio: rename variables in audio_pcm_sw_write(), Volker Rümelin, 2023/02/24
- [PATCH v3 13/15] audio: handle leftover audio frame from upsampling,
Volker Rümelin <=
- [PATCH v3 12/15] audio: make recording packet length calculation exact, Volker Rümelin, 2023/02/24
- [PATCH v3 14/15] audio/audio_template: substitute sw->hw with hw, Volker Rümelin, 2023/02/24
- [PATCH v3 15/15] audio: remove sw->ratio, Volker Rümelin, 2023/02/24