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module-vban: derive write position from frame counter

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Instead of writing packets sequentially and losing sync on any
frame gap, compute the write position from the VBAN header's
n_frames field. Out-of-order packets land at the correct
ringbuffer offset, matching how module-rtp handles this.

Only advance the writeindex when a packet extends the frontier
so that late arrivals fill gaps without moving the pointer
backwards.

Fixes: https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/5145
This commit is contained in:
thewrz 2026-02-27 21:54:22 -08:00
parent 354ec08b9b
commit 8ceb671cc8
2 changed files with 25 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

39
src/modules/module-vban/audio.c
View file

@ -98,38 +98,43 @@ static int vban_audio_receive(struct impl *impl, uint8_t *buffer, ssize_t len)
samples = SPA_MIN(hdr->format_nbs+1, plen / stride);
n_frames = hdr->n_frames;
if (impl->have_sync && impl->n_frames != n_frames) {
pw_log_info("unexpected frame (%d != %d)",
n_frames, impl->n_frames);
if (impl->samples_per_frame == 0) {
impl->samples_per_frame = samples;
} else if (samples != impl->samples_per_frame) {
pw_log_warn("samples_per_frame changed (%u != %u)",
samples, impl->samples_per_frame);
impl->samples_per_frame = samples;
impl->have_sync = false;
}
if (impl->have_sync && impl->n_frames != n_frames) {
pw_log_info("unexpected frame (%u != %u)",
n_frames, impl->n_frames);
}
impl->n_frames = n_frames + 1;
timestamp = impl->timestamp;
impl->timestamp += samples;
/* derive write position from frame counter, like module-rtp */
timestamp = n_frames * impl->samples_per_frame;
write = timestamp + impl->target_buffer;
filled = spa_ringbuffer_get_write_index(&impl->ring, &expected_write);
/* we always write to timestamp + delay */
write = timestamp + impl->target_buffer;
if (!impl->have_sync) {
pw_log_info("sync to timestamp:%u target:%u",
timestamp, impl->target_buffer);
pw_log_info("sync to n_frames:%u timestamp:%u target:%u",
n_frames, timestamp, impl->target_buffer);
/* we read from timestamp, keeping target_buffer of data
* in the ringbuffer. */
impl->ring.readindex = timestamp;
impl->ring.writeindex = write;
filled = impl->target_buffer;
expected_write = write;
spa_dll_init(&impl->dll);
spa_dll_set_bw(&impl->dll, SPA_DLL_BW_MAX, 128, impl->rate);
memset(impl->buffer, 0, BUFFER_SIZE);
impl->have_sync = true;
} else if (expected_write != write) {
pw_log_debug("unexpected write (%u != %u)",
write, expected_write);
}
if (filled + samples > BUFFER_SIZE / stride) {
@ -137,14 +142,17 @@ static int vban_audio_receive(struct impl *impl, uint8_t *buffer, ssize_t len)
BUFFER_SIZE / stride);
impl->have_sync = false;
} else {
pw_log_trace("got samples:%u", samples);
pw_log_trace("got n_frames:%u samples:%u", n_frames, samples);
spa_ringbuffer_write_data(&impl->ring,
impl->buffer,
BUFFER_SIZE,
(write * stride) & BUFFER_MASK,
&buffer[hlen], (samples * stride));
/* only advance writeindex if this extends the frontier */
write += samples;
spa_ringbuffer_write_update(&impl->ring, write);
if ((int32_t)(write - expected_write) > 0)
spa_ringbuffer_write_update(&impl->ring, write);
}
return 0;
}
@ -262,5 +270,6 @@ static int vban_audio_init(struct impl *impl, enum spa_direction direction)
else
impl->stream_events.process = vban_audio_process_playback;
impl->receive_vban = vban_audio_receive;
impl->samples_per_frame = 0;
return 0;
}

1
src/modules/module-vban/stream.c
View file

@ -61,6 +61,7 @@ struct impl {
struct vban_header header;
uint32_t timestamp;
uint32_t n_frames;
uint32_t samples_per_frame;
struct spa_ringbuffer ring;
uint8_t buffer[BUFFER_SIZE];