WASAPI Audio Input/Output Support

[Brad Isbell]

The Windows Audio Session API (WASAPI) is a modern API for audio playback/capture under Windows. It offers several benefits over the current DirectShow implementation in FFmpeg:

• ​Multi-channel support
• ​Loopback capture, for both entire output devices and for individual streams from applications
• ​Low-latency I/O without the need for proprietary ASIO
• ​Exclusive mode for further reducing latency

Sample Usage

Capture from multichannel soundcard:

ffmpeg -f wasapi -ar 96000 -ac 8 -i device="My Multichannel Soundcard" …

Capture in exclusive mode from soundcard named 'Soundcard':

ffmpeg -f wasapi -exclusive_mode true -i device="Soundcard" …

Capture loopback from soundcard named 'Soundcard':

ffmpeg -f wasapi -i loopback_device="Soundcard" …

Capture loopback from entire system:

ffmpeg -f wasapi -i loopback_system=true …

Capture loopback from app by name or PID:

ffmpeg -f wasapi -i loopback_application_pid=54321 …
ffmpeg -f wasapi -i loopback_application_name="Skifree" …

[Balling]

SDL_OpenAudio ffplay already uses WASAPI. Interesting that 8.1 is apparently not supported.

[Glenn C Newell]

This is a problem in that modern immersive surround formats have more than 8 channels, not to mention High Order Ambisonics. Other aspects of ffmpeg have channel support up to 22.2, but for playback SDL2 is a bottleneck.

A Related note, even given dshow and WASAPI support, it is very difficult/impossible to find windows binary builds with support for those.

[Brad Isbell]

Another use case that's popped up is capturing in 32-bit float. Several prosumer audio interfaces and recorders now support floating point audio capture. 32-bit float can be captured with WASAPI. Samples with values >±1.0 can be captured with WASAPI in exclusive mode. Gstreamer supports this today. If FFmpeg adds support, that goes a long way to enabling floating point capture in all the applications built on FFmpeg.

[Federico Gratti]

It would be great to have WASAPI on ffmpeg. Mainly to capture loopback from entire system and use it with the Screen Recording feature

[Juan Domingo]

ヽ༼ຈل͜ຈ༽ﾉ currently requesting for WASAPI ヽ༼ຈل͜ຈ༽ﾉ I need it for ... a private project lol