From 41e8f9ede41dedf96121f858fca20b3c809835cc Mon Sep 17 00:00:00 2001 From: "Ryan C. Gordon" Date: Tue, 2 Aug 2016 15:06:40 -0400 Subject: [PATCH] alsa: Implemented audio capture support! --- src/audio/alsa/SDL_alsa_audio.c | 68 +++++++++++++++++++++++++++++++-- 1 file changed, 65 insertions(+), 3 deletions(-) diff --git a/src/audio/alsa/SDL_alsa_audio.c b/src/audio/alsa/SDL_alsa_audio.c index 56e55cd25..ef3b4c706 100644 --- a/src/audio/alsa/SDL_alsa_audio.c +++ b/src/audio/alsa/SDL_alsa_audio.c @@ -29,6 +29,7 @@ #include #include +#include "SDL_assert.h" #include "SDL_timer.h" #include "SDL_audio.h" #include "../SDL_audiomem.h" @@ -42,8 +43,10 @@ static int (*ALSA_snd_pcm_open) (snd_pcm_t **, const char *, snd_pcm_stream_t, int); static int (*ALSA_snd_pcm_close) (snd_pcm_t * pcm); -static snd_pcm_sframes_t(*ALSA_snd_pcm_writei) +static snd_pcm_sframes_t (*ALSA_snd_pcm_writei) (snd_pcm_t *, const void *, snd_pcm_uframes_t); +static snd_pcm_sframes_t (*ALSA_snd_pcm_readi) + (snd_pcm_t *, void *, snd_pcm_uframes_t); static int (*ALSA_snd_pcm_recover) (snd_pcm_t *, int, int); static int (*ALSA_snd_pcm_prepare) (snd_pcm_t *); static int (*ALSA_snd_pcm_drain) (snd_pcm_t *); @@ -85,6 +88,7 @@ static int (*ALSA_snd_pcm_nonblock) (snd_pcm_t *, int); static int (*ALSA_snd_pcm_wait)(snd_pcm_t *, int); static int (*ALSA_snd_pcm_sw_params_set_avail_min) (snd_pcm_t *, snd_pcm_sw_params_t *, snd_pcm_uframes_t); +static int (*ALSA_snd_pcm_reset)(snd_pcm_t *); static int (*ALSA_snd_device_name_hint) (int, const char *, void ***); static char* (*ALSA_snd_device_name_get_hint) (const void *, const char *); static int (*ALSA_snd_device_name_free_hint) (void **); @@ -121,6 +125,7 @@ load_alsa_syms(void) SDL_ALSA_SYM(snd_pcm_open); SDL_ALSA_SYM(snd_pcm_close); SDL_ALSA_SYM(snd_pcm_writei); + SDL_ALSA_SYM(snd_pcm_readi); SDL_ALSA_SYM(snd_pcm_recover); SDL_ALSA_SYM(snd_pcm_prepare); SDL_ALSA_SYM(snd_pcm_drain); @@ -147,6 +152,7 @@ load_alsa_syms(void) SDL_ALSA_SYM(snd_pcm_nonblock); SDL_ALSA_SYM(snd_pcm_wait); SDL_ALSA_SYM(snd_pcm_sw_params_set_avail_min); + SDL_ALSA_SYM(snd_pcm_reset); SDL_ALSA_SYM(snd_device_name_hint); SDL_ALSA_SYM(snd_device_name_get_hint); SDL_ALSA_SYM(snd_device_name_free_hint); @@ -342,6 +348,57 @@ ALSA_GetDeviceBuf(_THIS) return (this->hidden->mixbuf); } +static int +ALSA_CaptureFromDevice(_THIS, void *buffer, int buflen) +{ + Uint8 *sample_buf = (Uint8 *) buffer; + const int frame_size = (((int) SDL_AUDIO_BITSIZE(this->spec.format)) / 8) * + this->spec.channels; + const int total_frames = buflen / frame_size; + snd_pcm_uframes_t frames_left = total_frames; + + SDL_assert((buflen % frame_size) == 0); + + while ( frames_left > 0 && SDL_AtomicGet(&this->enabled) ) { + /* !!! FIXME: This works, but needs more testing before going live */ + /* ALSA_snd_pcm_wait(this->hidden->pcm_handle, -1); */ + int status = ALSA_snd_pcm_readi(this->hidden->pcm_handle, + sample_buf, frames_left); + + if (status < 0) { + /*printf("ALSA: capture error %d\n", status);*/ + if (status == -EAGAIN) { + /* Apparently snd_pcm_recover() doesn't handle this case - + does it assume snd_pcm_wait() above? */ + SDL_Delay(1); + continue; + } + status = ALSA_snd_pcm_recover(this->hidden->pcm_handle, status, 0); + if (status < 0) { + /* Hmm, not much we can do - abort */ + fprintf(stderr, "ALSA read failed (unrecoverable): %s\n", + ALSA_snd_strerror(status)); + return -1; + } + continue; + } + + /*printf("ALSA: captured %d bytes\n", status * frame_size);*/ + sample_buf += status * frame_size; + frames_left -= status; + } + + swizzle_alsa_channels(this, buffer, total_frames - frames_left); + + return (total_frames - frames_left) * frame_size; +} + +static void +ALSA_FlushCapture(_THIS) +{ + ALSA_snd_pcm_reset(this->hidden->pcm_handle); +} + static void ALSA_CloseDevice(_THIS) { @@ -493,8 +550,9 @@ ALSA_OpenDevice(_THIS, void *handle, const char *devname, int iscapture) /* Open the audio device */ /* Name of device should depend on # channels in spec */ status = ALSA_snd_pcm_open(&pcm_handle, - get_audio_device(handle, this->spec.channels), - SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK); + get_audio_device(handle, this->spec.channels), + iscapture ? SND_PCM_STREAM_CAPTURE : SND_PCM_STREAM_PLAYBACK, + SND_PCM_NONBLOCK); if (status < 0) { ALSA_CloseDevice(this); @@ -757,6 +815,10 @@ ALSA_Init(SDL_AudioDriverImpl * impl) impl->CloseDevice = ALSA_CloseDevice; impl->Deinitialize = ALSA_Deinitialize; impl->FreeDeviceHandle = ALSA_FreeDeviceHandle; + impl->CaptureFromDevice = ALSA_CaptureFromDevice; + impl->FlushCapture = ALSA_FlushCapture; + + impl->HasCaptureSupport = SDL_TRUE; return 1; /* this audio target is available. */ }