Question about potential allocation issue

[travisjayday]

Hi there,

Let me preface this by saying I'm a noob at macOS ecosystem and I'm in the process of learning.

I've been reading over the source code and I've noticed something that I don't understand. This might be a bug, not sure. Why do you only allocate 6 * sizeof(...) in Blackhole_GetStreamPropertyDataSize?

BlackHole/BlackHole/BlackHole.c

Line 2457 in 21989c7

*outDataSize = 6 * sizeof(AudioStreamRangedDescription);

Should you not allocate NUM_CHANNELS * sizeof(...)? Is there a reason why 6?

I'm asking because in the originall NullAudio.h example from Apple, they allocate 2 * sizeof(...)

Maybe for two-channel audio?

[devinroth]

NullAudio only support 2 formats. 44.1k and 48k. Blackhole supports 44.1k, 48k, 88.2k, 96k, 176k, 192k. That’s where the difference between the 6 and the 2 comes from. Nothing to do with the number of channels. Yup I know, it’s confusing. Devin

…

On Dec 20, 2020, 5:39 PM -0800, Travis Ziegler ***@***.***>, wrote: Hi there, Let me preface this by saying I'm a noob at macOS ecosystem and I'm in the process of learning. I've been reading over the source code and I've noticed something that I don't understand. This might be a bug, not sure. Why do you only allocate 6 * sizeof(...) in Blackhole_GetStreamPropertyDataSize? https://github.com/ExistentialAudio/BlackHole/blob/21989c75ec0281c52f0e97d9e079490c087f21c3/BlackHole/BlackHole.c#L2457 Should you not allocate NUM_CHANNELS * sizeof(...)? Is there a reason why 6? I'm asking because in the originall NullAudio.h example from Apple, they allocate 2 * sizeof(...) Maybe for two-channel audio? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or unsubscribe.

[travisjayday]

Oh I see that makes sense.

Phew yeah, I'm realizing core audio is not too friendly so thanks for clarifying, Devin.

Travis