ALSA: implement channel layout for playback.

Currently quad, 5.0, 5.1 and 7.1 are implemented.
Implementing support for other formats/layouts and capture should be
straightforward.

5.0 and 7.1 support by Carl Eugen Hoyos.
Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavdevice/alsa-audio-common.c

@@ -30,6 +30,7 @@
 
 #include <alsa/asoundlib.h>
 #include "libavformat/avformat.h"
+#include "libavutil/avassert.h"
 
 #include "alsa-audio.h"
 
@@ -60,6 +61,127 @@ static av_cold snd_pcm_format_t codec_id_to_pcm_format(int codec_id)
     }
 }
 
+#define REORDER_OUT_50(NAME, TYPE) \
+static void alsa_reorder_ ## NAME ## _out_50(const void *in_v, void *out_v, int n) \
+{ \
+    const TYPE *in = in_v; \
+    TYPE      *out = out_v; \
+\
+    while (n-- > 0) { \
+        out[0] = in[0]; \
+        out[1] = in[1]; \
+        out[2] = in[3]; \
+        out[3] = in[4]; \
+        out[4] = in[2]; \
+        in  += 5; \
+        out += 5; \
+    } \
+}
+
+#define REORDER_OUT_51(NAME, TYPE) \
+static void alsa_reorder_ ## NAME ## _out_51(const void *in_v, void *out_v, int n) \
+{ \
+    const TYPE *in = in_v; \
+    TYPE      *out = out_v; \
+\
+    while (n-- > 0) { \
+        out[0] = in[0]; \
+        out[1] = in[1]; \
+        out[2] = in[4]; \
+        out[3] = in[5]; \
+        out[4] = in[2]; \
+        out[5] = in[3]; \
+        in  += 6; \
+        out += 6; \
+    } \
+}
+
+#define REORDER_OUT_71(NAME, TYPE) \
+static void alsa_reorder_ ## NAME ## _out_71(const void *in_v, void *out_v, int n) \
+{ \
+    const TYPE *in = in_v; \
+    TYPE      *out = out_v; \
+\
+    while (n-- > 0) { \
+        out[0] = in[0]; \
+        out[1] = in[1]; \
+        out[2] = in[4]; \
+        out[3] = in[5]; \
+        out[4] = in[2]; \
+        out[5] = in[3]; \
+        out[6] = in[6]; \
+        out[7] = in[7]; \
+        in  += 8; \
+        out += 8; \
+    } \
+}
+
+REORDER_OUT_50(int8, int8_t)
+REORDER_OUT_51(int8, int8_t)
+REORDER_OUT_71(int8, int8_t)
+REORDER_OUT_50(int16, int16_t)
+REORDER_OUT_51(int16, int16_t)
+REORDER_OUT_71(int16, int16_t)
+REORDER_OUT_50(int32, int32_t)
+REORDER_OUT_51(int32, int32_t)
+REORDER_OUT_71(int32, int32_t)
+REORDER_OUT_50(f32, float)
+REORDER_OUT_51(f32, float)
+REORDER_OUT_71(f32, float)
+
+#define FORMAT_I8  0
+#define FORMAT_I16 1
+#define FORMAT_I32 2
+#define FORMAT_F32 3
+
+#define PICK_REORDER(layout)\
+switch(format) {\
+    case FORMAT_I8:  s->reorder_func = alsa_reorder_int8_out_ ##layout;  break;\
+    case FORMAT_I16: s->reorder_func = alsa_reorder_int16_out_ ##layout; break;\
+    case FORMAT_I32: s->reorder_func = alsa_reorder_int32_out_ ##layout; break;\
+    case FORMAT_F32: s->reorder_func = alsa_reorder_f32_out_ ##layout;   break;\
+}
+
+static av_cold int find_reorder_func(AlsaData *s, int codec_id, int64_t layout, int out)
+{
+    int format;
+
+    /* reordering input is not currently supported */
+    if (!out)
+        return AVERROR(ENOSYS);
+
+    /* reordering is not needed for QUAD or 2_2 layout */
+    if (layout == AV_CH_LAYOUT_QUAD || layout == AV_CH_LAYOUT_2_2)
+        return 0;
+
+    switch (codec_id) {
+    case CODEC_ID_PCM_S8:
+    case CODEC_ID_PCM_U8:
+    case CODEC_ID_PCM_ALAW:
+    case CODEC_ID_PCM_MULAW: format = FORMAT_I8;  break;
+    case CODEC_ID_PCM_S16LE:
+    case CODEC_ID_PCM_S16BE:
+    case CODEC_ID_PCM_U16LE:
+    case CODEC_ID_PCM_U16BE: format = FORMAT_I16; break;
+    case CODEC_ID_PCM_S32LE:
+    case CODEC_ID_PCM_S32BE:
+    case CODEC_ID_PCM_U32LE:
+    case CODEC_ID_PCM_U32BE: format = FORMAT_I32; break;
+    case CODEC_ID_PCM_F32LE:
+    case CODEC_ID_PCM_F32BE: format = FORMAT_F32; break;
+    default:                 return AVERROR(ENOSYS);
+    }
+
+    if      (layout == AV_CH_LAYOUT_5POINT0_BACK || layout == AV_CH_LAYOUT_5POINT0)
+        PICK_REORDER(50)
+    else if (layout == AV_CH_LAYOUT_5POINT1_BACK || layout == AV_CH_LAYOUT_5POINT1)
+        PICK_REORDER(51)
+    else if (layout == AV_CH_LAYOUT_7POINT1)
+        PICK_REORDER(71)
+
+    return s->reorder_func ? 0 : AVERROR(ENOSYS);
+}
+
 av_cold int ff_alsa_open(AVFormatContext *ctx, snd_pcm_stream_t mode,
                          unsigned int *sample_rate,
                          int channels, enum CodecID *codec_id)
@@ -71,6 +193,7 @@ av_cold int ff_alsa_open(AVFormatContext *ctx, snd_pcm_stream_t mode,
     snd_pcm_t *h;
     snd_pcm_hw_params_t *hw_params;
     snd_pcm_uframes_t buffer_size, period_size;
+    int64_t layout = ctx->streams[0]->codec->channel_layout;
 
     if (ctx->filename[0] == 0) audio_device = "default";
     else                       audio_device = ctx->filename;
@@ -163,6 +286,21 @@ av_cold int ff_alsa_open(AVFormatContext *ctx, snd_pcm_stream_t mode,
 
     snd_pcm_hw_params_free(hw_params);
 
+    if (channels > 2 && layout) {
+        if (find_reorder_func(s, *codec_id, layout, mode == SND_PCM_STREAM_PLAYBACK) < 0) {
+            char name[128];
+            av_get_channel_layout_string(name, sizeof(name), channels, layout);
+            av_log(ctx, AV_LOG_WARNING, "ALSA channel layout unknown or unimplemented for %s %s.\n",
+                   name, mode == SND_PCM_STREAM_PLAYBACK ? "playback" : "capture");
+        }
+        if (s->reorder_func) {
+            s->reorder_buf_size = buffer_size;
+            s->reorder_buf = av_malloc(s->reorder_buf_size * s->frame_size);
+            if (!s->reorder_buf)
+                goto fail1;
+        }
+    }
+
     s->h = h;
     return 0;
 
@@ -177,6 +315,7 @@ av_cold int ff_alsa_close(AVFormatContext *s1)
 {
     AlsaData *s = s1->priv_data;
 
+    av_freep(&s->reorder_buf);
     snd_pcm_close(s->h);
     return 0;
 }
@@ -201,3 +340,19 @@ int ff_alsa_xrun_recover(AVFormatContext *s1, int err)
     }
     return err;
 }
+
+int ff_alsa_extend_reorder_buf(AlsaData *s, int min_size)
+{
+    int size = s->reorder_buf_size;
+    void *r;
+
+    av_assert0(size != 0);
+    while (size < min_size)
+        size *= 2;
+    r = av_realloc(s->reorder_buf, size * s->frame_size);
+    if (!r)
+        return AVERROR(ENOMEM);
+    s->reorder_buf = r;
+    s->reorder_buf_size = size;
+    return 0;
+}

libavdevice/alsa-audio-enc.c

@@ -76,7 +76,15 @@ static int audio_write_packet(AVFormatContext *s1, AVPacket *pkt)
     int size     = pkt->size;
     uint8_t *buf = pkt->data;
 
-    while((res = snd_pcm_writei(s->h, buf, size / s->frame_size)) < 0) {
+    size /= s->frame_size;
+    if (s->reorder_func) {
+        if (size > s->reorder_buf_size)
+            if (ff_alsa_extend_reorder_buf(s, size))
+                return AVERROR(ENOMEM);
+        s->reorder_func(buf, s->reorder_buf, size);
+        buf = s->reorder_buf;
+    }
+    while ((res = snd_pcm_writei(s->h, buf, size)) < 0) {
         if (res == -EAGAIN) {
 
             return AVERROR(EAGAIN);

libavdevice/alsa-audio.h

@@ -47,6 +47,9 @@ typedef struct {
     int period_size; ///< bytes per sample * channels
     int sample_rate; ///< sample rate set by user
     int channels;    ///< number of channels set by user
+    void (*reorder_func)(const void *, void *, int);
+    void *reorder_buf;
+    int reorder_buf_size; ///< in frames
 } AlsaData;
 
 /**
@@ -86,4 +89,6 @@ int ff_alsa_close(AVFormatContext *s1);
  */
 int ff_alsa_xrun_recover(AVFormatContext *s1, int err);
 
+int ff_alsa_extend_reorder_buf(AlsaData *s, int size);
+
 #endif /* AVDEVICE_ALSA_AUDIO_H */