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[PATCH v2 15/17] audio: handle leftover audio frame from upsampling
From: |
Volker Rümelin |
Subject: |
[PATCH v2 15/17] audio: handle leftover audio frame from upsampling |
Date: |
Mon, 6 Feb 2023 19:52:35 +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>
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
- Re: [PATCH v2 09/17] audio/mixeng: calculate number of input frames, (continued)
- [PATCH v2 10/17] audio: wire up st_rate_frames_in(), Volker Rümelin, 2023/02/06
- [PATCH v2 11/17] audio: replace the resampling loop in audio_pcm_sw_read(), Volker Rümelin, 2023/02/06
- [PATCH v2 04/17] audio: replace the resampling loop in audio_pcm_sw_write(), Volker Rümelin, 2023/02/06
- [PATCH v2 12/17] audio: rename variables in audio_pcm_sw_read(), Volker Rümelin, 2023/02/06
- [PATCH v2 13/17] audio/mixeng: calculate number of output frames, Volker Rümelin, 2023/02/06
- [PATCH v2 15/17] audio: handle leftover audio frame from upsampling,
Volker Rümelin <=
- [PATCH v2 14/17] audio: wire up st_rate_frames_out(), Volker Rümelin, 2023/02/06
- [PATCH v2 17/17] audio: remove sw->ratio, Volker Rümelin, 2023/02/06
- [PATCH v2 16/17] audio/audio_template: substitute sw->hw with hw, Volker Rümelin, 2023/02/06