Revert "ao_coreaudio: switch to ao_read_data_nonblocking()" #13902

m154k1 · 2024-04-16T16:41:12Z

Fixes #13880

This reverts commit 36d5b52.

github-actions · 2024-04-16T16:53:43Z

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Dudemanguy · 2024-04-16T20:32:21Z

Maybe 0341a6f needs to be reverted too?

sfan5 · 2024-04-16T20:57:53Z

Maybe 0341a6f needs to be reverted too?

No, the blocking function does not guarantee that ret_samples == samples either.

kasper93 · 2024-04-16T23:30:46Z

Is it possible to do the same for ao_avfoundation?

diff --git a/audio/out/ao_avfoundation.m b/audio/out/ao_avfoundation.m
index 7654916519..61bf39620e 100644
--- a/audio/out/ao_avfoundation.m
+++ b/audio/out/ao_avfoundation.m
@@ -76,12 +76,7 @@ static void feed(struct ao *ao)
     int64_t cur_time_mp = mp_time_ns();
     int64_t end_time_av = MPMAX(p->end_time_av, cur_time_av);
     int64_t time_delta = CMTimeGetNanoseconds(CMTimeMake(request_sample_count, samplerate));
-    int real_sample_count = ao_read_data_nonblocking(ao, data, request_sample_count, end_time_av - cur_time_av + cur_time_mp + time_delta);
-    if (real_sample_count == 0) {
-        // avoid spinning by blocking the thread
-        mp_sleep_ns(10000000);
-        goto finish;
-    }
+    int real_sample_count = ao_read_data(ao, data, request_sample_count, end_time_av - cur_time_av + cur_time_mp + time_delta);

     if ((err = CMBlockBufferCreateWithMemoryBlock(
         NULL,

Akemi · 2024-04-17T17:41:27Z

@ruihe774 see @kasper93 comment above.

ruihe774 · 2024-04-17T18:14:47Z

Is it possible to do the same for ao_avfoundation?

diff --git a/audio/out/ao_avfoundation.m b/audio/out/ao_avfoundation.m
index 7654916519..61bf39620e 100644
--- a/audio/out/ao_avfoundation.m
+++ b/audio/out/ao_avfoundation.m
@@ -76,12 +76,7 @@ static void feed(struct ao *ao)
     int64_t cur_time_mp = mp_time_ns();
     int64_t end_time_av = MPMAX(p->end_time_av, cur_time_av);
     int64_t time_delta = CMTimeGetNanoseconds(CMTimeMake(request_sample_count, samplerate));
-    int real_sample_count = ao_read_data_nonblocking(ao, data, request_sample_count, end_time_av - cur_time_av + cur_time_mp + time_delta);
-    if (real_sample_count == 0) {
-        // avoid spinning by blocking the thread
-        mp_sleep_ns(10000000);
-        goto finish;
-    }
+    int real_sample_count = ao_read_data(ao, data, request_sample_count, end_time_av - cur_time_av + cur_time_mp + time_delta);

     if ((err = CMBlockBufferCreateWithMemoryBlock(
         NULL,

@kasper93 avfoundation can well handle audio buffer of variable length.

ruihe774 · 2024-04-17T18:19:05Z

audio/out/ao_coreaudio.c

@@ -89,7 +89,7 @@ static OSStatus render_cb_lpcm(void *ctx, AudioUnitRenderActionFlags *aflags,

    int64_t end = mp_time_ns();
    end += p->hw_latency_ns + ca_get_latency(ts) + ca_frames_to_ns(ao, frames);
-    int samples = ao_read_data_nonblocking(ao, planes, frames, end);
+    int samples = ao_read_data(ao, planes, frames, end);


I think we should not use samples returned from ao_read_data, which may be less than requested. The original implementation did not use it and always submit buffers of requested length to CoreAudio. CoreAudio expect the buffer length be equal to requested.

sfan5 · 2024-04-17T18:24:26Z

@kasper93 avfoundation can well handle audio buffer of variable length.

The point is that sleeping 10ms when no samples are returned makes no sense. You can as well just use the blocking variant.

kasper93 · 2024-04-17T18:27:20Z

@kasper93 avfoundation can well handle audio buffer of variable length.

That's cool. Let me rephrase my question. Could we remove this terrible hack of blocking the audio thread for 10 ms, by all and any means necessary?

ruihe774 · 2024-04-17T18:49:56Z

I don't think "sleeping 10ms" and "blocking variant" are the same thing. ao_read_data, the "blocking variant", does not block when "no samples are returned". It only blocks on mutex contention. We still need to sleep for "no samples are returned" even if ao_read_data is used.

FWIW, #11955 (comment), #11955 (comment)

sfan5 · 2024-04-17T19:07:18Z

I don't think "sleeping 10ms" and "blocking variant" are the same thing. ao_read_data, the "blocking variant", does not block when "no samples are returned". It only blocks on mutex contention.

I assumed that the sleep was added after the author noticed that it would spuriously return zero (usually on mutex contention, like you said). If this isn't the case then that doesn't apply ofc.
I haven't investigated closely but if the lack of samples instead happens near EOF it sounds like the core is maybe not pausing the AO early enough?

ruihe774 · 2024-04-17T19:16:45Z

I don't think "sleeping 10ms" and "blocking variant" are the same thing. ao_read_data, the "blocking variant", does not block when "no samples are returned". It only blocks on mutex contention.

I assumed that the sleep was added after the author noticed that it would spuriously return zero (usually on mutex contention, like you said). If this isn't the case then that doesn't apply ofc. I haven't investigated closely but if the lack of samples instead happens near EOF it sounds like the core is maybe not pausing the AO early enough?

The core does not stop AO until EOF. In fact, there is no API for core to tell pull-based AO to "stop requesting data but continue playing enqueued data". Some AO, like pipewire, will starve and spin near EOF; but because pipewire usually has very short device buffer (1024 samples usually), it will not spin too many times. This is not the case for avfoundation, which can be starving for more than 1 second near EOF.

ruihe774 · 2024-04-17T19:20:26Z

@sfan5 why you've merged it? I have a ongoing review #13902 (comment)

sfan5 · 2024-04-17T19:30:35Z

The core does not stop AO until EOF. In fact, there is no API for core to tell pull-based AO to "stop requesting data but continue playing enqueued data". Some AO, like pipewire, will starve and spin near EOF; but because pipewire usually has very short device buffer (1024 samples usually), it will not spin too many times.

I see. Maybe that'd be a good thing to address in the future. Just sleeping in the ao thread feels like a dirty fix.

@sfan5 why you've merged it? I have a ongoing review #13902 (comment)

We decided on IRC that we are okay with merging the revert since OP confirmed that it helps their case.
The other change has been there longer (0341a6f) and we're not aware of it causing issues yet. So that can be solved afterwards.

Akemi · 2024-04-17T19:31:26Z

it was actually because of me. i didn't see your comment and i felt like reverting to the state before would be reasonable. we were talking about the release and what is blocking it on irc and decided to merge it.

20:43 der_richter from the comments on the issue it seems to fix the issue. can't really confirm since i didn't encounter it.
20:45 if you are fine with it, i would merge the revert commit for now. since we don't really have anyone who is well versed with the coreaudio stuff, i doubt we could get a better solution in a timely fashion? and if we do we can still merge another fix.

i am still very much interested in a proper solution, if possible.

ruihe774 · 2024-04-17T19:47:41Z

We decided on IRC that we are okay with merging the revert since OP confirmed that it helps their case. The other change has been there longer (0341a6f) and we're not aware of it causing issues yet. So that can be solved afterwards.

0341a6f is a hacky fix for ae908a7 (see #12643 (comment)). Since we've reverted ae908a7, 0341a6f is no longer necessary. Giving there are no issues reported for it, I'm OK with current solution.

Akemi · 2024-04-17T21:03:59Z

we actually have a problem with 0341a6f, this one #13348, and i was contemplating of reverting it too.

should we revert it too or do you think there is a better way of handling it @ruihe774?

ruihe774 · 2024-04-18T04:25:56Z

we actually have a problem with 0341a6f, this one #13348, and i was contemplating of reverting it too.

should we revert it too or do you think there is a better way of handling it @ruihe774?

I think we need to revert it. cc @handlerug

low-batt · 2024-04-18T21:27:28Z

I just confirmed that #13348 still reproduces with libmpv built from the current master. This PR did not fix it.

ruihe774 · 2024-04-19T07:12:34Z

I just confirmed that #13348 still reproduces with libmpv built from the current master. This PR did not fix it.

Yes. We need another revert for 0341a6f. I'm still waiting for response from @handlerug.

handlerug · 2024-04-19T07:15:12Z

Go ahead, I don’t see any purpose in that commit if we are now back to blocking like before.On 19 Apr 2024, at 10:13, Rui He ***@***.***> wrote: I just confirmed that #13348 still reproduces with libmpv built from the current master. This PR did not fix it. Yes. We need another revert for 0341a6f. I'm still waiting response from @handlerug. —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you were mentioned.Message ID: ***@***.***>

Revert "ao_coreaudio: switch to ao_read_data_nonblocking()"

b55c329

This reverts commit 36d5b52.

Akemi added this to the Release v0.38.0 milestone Apr 17, 2024

ruihe774 suggested changes Apr 17, 2024

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sfan5 merged commit 7a8a92b into mpv-player:master Apr 17, 2024
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ruihe774 mentioned this pull request Apr 18, 2024

Support for Spatial Audio on macOS Monterey iina/iina#3444

Closed

m154k1 deleted the revert-36d5b52 branch April 18, 2024 07:29

This was referenced Apr 19, 2024

Revert "ao_coreaudio: signal buffer underruns" #13936

Merged

ao: EOF handling for pull-based AO #13967

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Revert "ao_coreaudio: switch to ao_read_data_nonblocking()" #13902

Revert "ao_coreaudio: switch to ao_read_data_nonblocking()" #13902

m154k1 commented Apr 16, 2024

github-actions bot commented Apr 16, 2024

Dudemanguy commented Apr 16, 2024

sfan5 commented Apr 16, 2024

kasper93 commented Apr 16, 2024

Akemi commented Apr 17, 2024

ruihe774 commented Apr 17, 2024

ruihe774 Apr 17, 2024

sfan5 commented Apr 17, 2024

kasper93 commented Apr 17, 2024 •

edited

ruihe774 commented Apr 17, 2024 •

edited

sfan5 commented Apr 17, 2024

ruihe774 commented Apr 17, 2024 •

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ruihe774 commented Apr 17, 2024

sfan5 commented Apr 17, 2024

Akemi commented Apr 17, 2024

ruihe774 commented Apr 17, 2024

Akemi commented Apr 17, 2024

ruihe774 commented Apr 18, 2024

low-batt commented Apr 18, 2024

ruihe774 commented Apr 19, 2024 •

edited

handlerug commented Apr 19, 2024 via email

Revert "ao_coreaudio: switch to ao_read_data_nonblocking()" #13902

Revert "ao_coreaudio: switch to ao_read_data_nonblocking()" #13902

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m154k1 commented Apr 16, 2024

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