From e1e6a6fcc9921a76a32109af515146f85ccc5f84 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Volker=20R=C3=BCmelin?= Date: Fri, 24 Feb 2023 20:05:53 +0100 Subject: [PATCH] audio: handle leftover audio frame from upsampling MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Acked-by: Marc-André Lureau Signed-off-by: Volker Rümelin Message-Id: <20230224190555.7409-13-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;