Add a52 output plugin

Added (experimental) a52 output plugin.
The plugin requires libavcodec as the audio encoding engine.

See doc/a52.txt for the usage.

2 files changed, 647 insertions, 0 deletions

diff --git a/a52/Makefile.am b/a52/Makefile.am
new file mode 100644
index 0000000..4021496
--- /dev/null
+++ b/a52/Makefile.am
@@ -0,0 +1,9 @@
+asound_module_pcm_a52_LTLIBRARIES = libasound_module_pcm_a52.la
+
+asound_module_pcm_a52dir = $(libdir)/alsa-lib
+
+AM_CFLAGS = -Wall -g @ALSA_CFLAGS@ @AVCODEC_CFLAGS@
+AM_LDFLAGS = -module -avoid-version -export-dynamic
+
+libasound_module_pcm_a52_la_SOURCES = pcm_a52.c
+libasound_module_pcm_a52_la_LIBADD = @ALSA_LIBS@ @AVCODEC_LIBS@
diff --git a/a52/pcm_a52.c b/a52/pcm_a52.c
new file mode 100644
index 0000000..3d376e2
--- /dev/null
+++ b/a52/pcm_a52.c
@@ -0,0 +1,638 @@
+/*
+ * A52 Output Plugin
+ *
+ * Copyright (c) 2006 by Takashi Iwai <tiwai@suse.de>
+ *
+ * This library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <stdio.h>
+#include <string.h>
+#define __USE_XOPEN
+#include <unistd.h>
+#include <alsa/asoundlib.h>
+#include <alsa/pcm_external.h>
+#include <ffmpeg/avcodec.h>
+
+struct a52_ctx {
+	snd_pcm_ioplug_t io;
+	snd_pcm_t *slave;
+	AVCodec *codec;
+	AVCodecContext *avctx;
+	snd_pcm_format_t format;
+	unsigned int channels;
+	unsigned int rate;
+	unsigned int bitrate;
+	short *inbuf;
+	unsigned char *outbuf;
+	int outbuf_size;
+	snd_pcm_uframes_t transfer;
+	int remain;
+	int filled;
+	unsigned int slave_period_size;
+	unsigned int slave_buffer_size;
+	snd_pcm_hw_params_t *hw_params;
+};
+
+/* convert to SPDIF output */
+static void convert_data(struct a52_ctx *rec)
+{
+	int out_bytes;
+
+	out_bytes = avcodec_encode_audio(rec->avctx, rec->outbuf + 8,
+					 rec->outbuf_size - 8,
+					 rec->inbuf);
+	rec->outbuf[0] = 0x72;
+	rec->outbuf[1] = 0xf8;
+	rec->outbuf[2] = 0x1f;
+	rec->outbuf[3] = 0x4e;
+	rec->outbuf[4] = 0x01;
+	rec->outbuf[5] = rec->outbuf[5] & 7;
+	rec->outbuf[6] = (out_bytes * 8) & 0xff;
+	rec->outbuf[7] = ((out_bytes * 8) >> 8) & 0xff;
+	if (rec->format == SND_PCM_FORMAT_S16_LE)
+		swab(rec->outbuf + 8, rec->outbuf + 8, out_bytes);
+	memset(rec->outbuf +  8 + out_bytes, 0,
+	       rec->outbuf_size - 8 - out_bytes);
+	rec->remain = rec->outbuf_size / 4;
+	rec->filled = 0;
+}
+
+static int write_out_pending(snd_pcm_ioplug_t *io ATTRIBUTE_UNUSED,
+			     struct a52_ctx *rec)
+{
+	int err, ofs = 0;
+
+	if (! rec->remain)
+		return 0;
+
+	while (rec->remain) {
+		err = snd_pcm_writei(rec->slave, rec->outbuf + ofs, rec->remain);
+		if (err < 0)
+			return err;
+		else if (! err)
+			break;
+		if (err < rec->remain)
+			ofs += (rec->remain - err) * 4;
+		rec->remain -= err;
+	}
+	if (rec->remain && ofs)
+		memmove(rec->outbuf, rec->outbuf + ofs, rec->remain * 4);
+	return 0;
+}
+
+static int a52_drain(snd_pcm_ioplug_t *io)
+{
+	struct a52_ctx *rec = io->private_data;
+	int err;
+
+	if (rec->filled) {
+		memset(rec->inbuf + rec->filled * io->channels, 0,
+		       (rec->avctx->frame_size - rec->filled) * io->channels * 2);
+		convert_data(rec);
+	}
+	err = write_out_pending(io, rec);
+	if (err < 0)
+		return err;
+	snd_pcm_drain(rec->slave);
+	return 0;
+}
+
+static int check_interleaved(const snd_pcm_channel_area_t *areas,
+			     unsigned int channels)
+{
+	unsigned int ch;
+
+	if (channels > 4) /* we need re-routing for 6 channels */
+		return 0;
+
+	for (ch = 0; ch < channels; ch++) {
+		if (areas[ch].addr != areas[0].addr ||
+		    areas[ch].first != ch * 16 ||
+		    areas[ch].step != channels * 16)
+			return 0;
+	}
+	return 1;
+}
+
+static int fill_data(snd_pcm_ioplug_t *io,
+		     const snd_pcm_channel_area_t *areas,
+		     unsigned int offset, unsigned int size,
+		     int interleaved)
+{
+	struct a52_ctx *rec = io->private_data;
+	unsigned int len = rec->avctx->frame_size - rec->filled;
+	short *src, *dst;
+	unsigned int src_step;
+	int err;
+
+	if ((err = write_out_pending(io, rec)) < 0)
+		return err;
+
+	if (size > len)
+		size = len;
+
+	dst = rec->inbuf + rec->filled * io->channels;
+	if (interleaved) {
+		memcpy(dst, areas->addr + offset * io->channels * 2,
+		       size * io->channels * 2);
+	} else {
+		unsigned int i, ch, dst_step;
+		short *dst1;
+		static unsigned int ch_index[3][6] = {
+			{ 0, 1 },
+			{ 0, 1, 2, 3 },
+			{ 0, 4, 1, 2, 3, 5 },
+		};
+		/* flatten copy to n-channel interleaved */
+		dst_step = io->channels;
+		for (ch = 0; ch < io->channels; ch++, dst++) {
+			const snd_pcm_channel_area_t *ap;
+			ap = &areas[ch_index[io->channels / 2 - 1][ch]];
+			dst1 = dst;
+			src = (short *)(ap->addr +
+					(ap->first + offset * ap->step) / 8);
+			src_step = ap->step / 16; /* in word */
+			for (i = 0; i < size; i++) {
+				*dst1 = *src;
+				src += src_step;
+				dst1 += dst_step;
+			}
+		}
+	}
+	rec->filled += size;
+	if (rec->filled == rec->avctx->frame_size) {
+		convert_data(rec);
+		write_out_pending(io, rec);
+	}
+	return (int)size;
+}
+
+static snd_pcm_sframes_t a52_transfer(snd_pcm_ioplug_t *io,
+				      const snd_pcm_channel_area_t *areas,
+				      snd_pcm_uframes_t offset,
+				      snd_pcm_uframes_t size)
+{
+	struct a52_ctx *rec = io->private_data;
+	snd_pcm_sframes_t result = 0;
+	int err = 0;
+	int interleaved = check_interleaved(areas, io->channels);
+
+	do {
+		err = fill_data(io, areas, offset, size, interleaved);
+		if (err < 0)
+			break;
+		offset += (unsigned int)err;
+		size -= (unsigned int)err;
+		result += err;
+		rec->transfer += err;
+	} while (size);
+	return result > 0 ? result : err;
+}
+
+static snd_pcm_sframes_t a52_pointer(snd_pcm_ioplug_t *io)
+{
+	struct a52_ctx *rec = io->private_data;
+	snd_pcm_sframes_t delay;
+	snd_pcm_state_t state;
+	int err;
+
+	state = snd_pcm_state(rec->slave);
+	if (state == SND_PCM_STATE_RUNNING ||
+	    state == SND_PCM_STATE_DRAINING) {
+		if ((err = snd_pcm_delay(rec->slave, &delay)) < 0)
+			return err;
+	} else
+		return 0;
+
+	if (delay < 0 || delay >= (snd_pcm_sframes_t)rec->slave_buffer_size)
+		delay = 0;
+	delay = (snd_pcm_sframes_t)io->appl_ptr - delay;
+	if (delay < 0) {
+		delay += io->buffer_size;
+		if (delay < 0)
+			delay = 0;
+	}
+	delay %= io->buffer_size;
+	return delay;
+}
+
+static int a52_slave_hw_params_half(struct a52_ctx *rec)
+{
+	int err;
+
+	if ((err = snd_pcm_hw_params_malloc(&rec->hw_params)) < 0)
+		return err;
+
+	if ((err = snd_pcm_hw_params_any(rec->slave, rec->hw_params)) < 0) {
+		SNDERR("Cannot get slave hw_params");
+		goto out;
+	}
+	if ((err = snd_pcm_hw_params_set_access(rec->slave, rec->hw_params,
+						SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
+		SNDERR("Cannot set slave access RW_INTERLEAVED");
+		goto out;
+	}
+	if ((err = snd_pcm_hw_params_set_channels(rec->slave, rec->hw_params, 2)) < 0) {
+		SNDERR("Cannot set slave channels 2");
+		goto out;
+	}
+	if ((err = snd_pcm_hw_params_set_format(rec->slave, rec->hw_params,
+						rec->format)) < 0) {
+		SNDERR("Cannot set slave format");
+		goto out;
+	}
+	if ((err = snd_pcm_hw_params_set_rate(rec->slave, rec->hw_params, rec->rate, 0)) < 0) {
+		SNDERR("Cannot set slave rate %d", rec->rate);
+		goto out;
+	}
+	return 0;
+
+ out:
+	free(rec->hw_params);
+	rec->hw_params = NULL;
+	return err;
+}
+
+static int a52_hw_params(snd_pcm_ioplug_t *io,
+			 snd_pcm_hw_params_t *params ATTRIBUTE_UNUSED)
+{
+	struct a52_ctx *rec = io->private_data;
+	snd_pcm_uframes_t period_size;
+	snd_pcm_uframes_t buffer_size;
+	int err;
+
+	if (! rec->hw_params) {
+		err = a52_slave_hw_params_half(rec);
+		if (err < 0)
+			return err;
+	}
+	period_size = io->period_size;
+	if ((err = snd_pcm_hw_params_set_period_size_near(rec->slave, rec->hw_params,
+							  &period_size, NULL)) < 0) {
+		SNDERR("Cannot set slave period size %ld", period_size);
+		return err;
+	}
+	buffer_size = io->buffer_size;
+	if ((err = snd_pcm_hw_params_set_buffer_size_near(rec->slave, rec->hw_params,
+							  &buffer_size)) < 0) {
+		SNDERR("Cannot set slave buffer size %ld", buffer_size);
+		return err;
+	}
+	if ((err = snd_pcm_hw_params(rec->slave, rec->hw_params)) < 0) {
+		SNDERR("Cannot set slave hw_params");
+		return err;
+	}
+	rec->slave_period_size = period_size;
+	rec->slave_buffer_size = buffer_size;
+
+	return 0;
+}
+
+static int a52_hw_free(snd_pcm_ioplug_t *io)
+{
+	struct a52_ctx *rec = io->private_data;
+
+	free(rec->hw_params);
+	rec->hw_params = NULL;
+	return snd_pcm_hw_free(rec->slave);
+}
+
+static int a52_sw_params(snd_pcm_ioplug_t *io, snd_pcm_sw_params_t *params)
+{
+	struct a52_ctx *rec = io->private_data;
+	snd_pcm_sw_params_t *sparams;
+	snd_pcm_uframes_t avail_min, start_threshold;
+	int len;
+
+	snd_pcm_sw_params_get_avail_min(params, &avail_min);
+	snd_pcm_sw_params_get_start_threshold(params, &start_threshold);
+
+	len = avail_min;
+	len += (int)rec->slave_buffer_size - (int)io->buffer_size;
+	if (len < 0)
+		avail_min = 1;
+	else
+		avail_min = len;
+	snd_pcm_sw_params_alloca(&sparams);
+	snd_pcm_sw_params_current(rec->slave, sparams);
+	snd_pcm_sw_params_set_avail_min(rec->slave, sparams, avail_min);
+	snd_pcm_sw_params_set_start_threshold(rec->slave, sparams,
+					      start_threshold);
+
+	return snd_pcm_sw_params(rec->slave, sparams);
+}
+
+static int a52_start(snd_pcm_ioplug_t *io)
+{
+	struct a52_ctx *rec = io->private_data;
+
+	snd_pcm_start(rec->slave);
+	return 0;
+}
+
+static int a52_stop(snd_pcm_ioplug_t *io)
+{
+	struct a52_ctx *rec = io->private_data;
+
+	snd_pcm_drop(rec->slave);
+	return 0;
+}
+
+static void a52_free(struct a52_ctx *rec)
+{
+	if (rec->avctx) {
+		avcodec_close(rec->avctx);
+		av_free(rec->avctx);
+		rec->avctx = NULL;
+	}
+	free(rec->inbuf);
+	rec->inbuf = NULL;
+	free(rec->outbuf);
+	rec->outbuf = NULL;
+}
+
+static int a52_prepare(snd_pcm_ioplug_t *io)
+{
+	struct a52_ctx *rec = io->private_data;
+
+	a52_free(rec);
+
+	rec->avctx = avcodec_alloc_context();
+	if (! rec->avctx)
+		return -ENOMEM;
+
+	rec->avctx->bit_rate = rec->bitrate * 1000;
+	rec->avctx->sample_rate = io->rate;
+	rec->avctx->channels = io->channels;
+
+	if (avcodec_open(rec->avctx, rec->codec) < 0)
+		return -EINVAL;
+
+	rec->inbuf = malloc(rec->avctx->frame_size * 2 * io->channels);
+	if (! rec->inbuf)
+		return -ENOMEM;
+	rec->outbuf_size = rec->avctx->frame_size * 4;
+	rec->outbuf = malloc(rec->outbuf_size);
+	if (! rec->outbuf)
+		return -ENOMEM;
+
+	rec->transfer = 0;
+	rec->remain = 0;
+	rec->filled = 0;
+
+	return snd_pcm_prepare(rec->slave);
+}
+
+static int a52_poll_descriptors_count(snd_pcm_ioplug_t *io)
+{
+	struct a52_ctx *rec = io->private_data;
+	return snd_pcm_poll_descriptors_count(rec->slave);
+}
+
+static int a52_poll_descriptors(snd_pcm_ioplug_t *io, struct pollfd *pfd,
+				unsigned int space)
+{
+	struct a52_ctx *rec = io->private_data;
+	return snd_pcm_poll_descriptors(rec->slave, pfd, space);
+}
+
+static int a52_poll_revents(snd_pcm_ioplug_t *io, struct pollfd *pfd,
+			    unsigned int nfds, unsigned short *revents)
+{
+	struct a52_ctx *rec = io->private_data;
+	return snd_pcm_poll_descriptors_revents(rec->slave, pfd, nfds, revents);
+}
+
+static int a52_close(snd_pcm_ioplug_t *io)
+{
+	struct a52_ctx *rec = io->private_data;
+
+	a52_free(rec);
+	if (rec->slave)
+		snd_pcm_close(rec->slave);
+	return 0;
+}
+			      
+static snd_pcm_ioplug_callback_t a52_ops = {
+	.start = a52_start,
+	.stop = a52_stop,
+	.pointer = a52_pointer,
+	.transfer = a52_transfer,
+	.close = a52_close,
+	.hw_params = a52_hw_params,
+	.hw_free = a52_hw_free,
+	.sw_params = a52_sw_params,
+	.prepare = a52_prepare,
+	.drain = a52_drain,
+	.poll_descriptors_count = a52_poll_descriptors_count,
+	.poll_descriptors = a52_poll_descriptors,
+	.poll_revents = a52_poll_revents,
+};
+
+#define A52_FRAME_SIZE	1536
+
+#define ARRAY_SIZE(ary)	(sizeof(ary)/sizeof(ary[0]))
+
+static int a52_set_hw_constraint(struct a52_ctx *rec)
+{
+	unsigned int accesses[] = {
+		SND_PCM_ACCESS_MMAP_INTERLEAVED,
+		SND_PCM_ACCESS_MMAP_NONINTERLEAVED,
+		SND_PCM_ACCESS_RW_INTERLEAVED,
+		SND_PCM_ACCESS_RW_NONINTERLEAVED
+	};
+	unsigned int formats[] = { SND_PCM_FORMAT_S16 };
+	int err;
+	snd_pcm_uframes_t buffer_max;
+	unsigned int period_bytes, max_periods;
+
+	if ((err = snd_pcm_ioplug_set_param_list(&rec->io, SND_PCM_IOPLUG_HW_ACCESS,
+						 ARRAY_SIZE(accesses), accesses)) < 0 ||
+	    (err = snd_pcm_ioplug_set_param_list(&rec->io, SND_PCM_IOPLUG_HW_FORMAT,
+						 ARRAY_SIZE(formats), formats)) < 0 ||
+	    (err = snd_pcm_ioplug_set_param_minmax(&rec->io, SND_PCM_IOPLUG_HW_CHANNELS,
+						   rec->channels, rec->channels)) < 0 ||
+	    (err = snd_pcm_ioplug_set_param_minmax(&rec->io, SND_PCM_IOPLUG_HW_RATE,
+						   rec->rate, rec->rate)) < 0)
+		return err;
+
+	if ((err = a52_slave_hw_params_half(rec)) < 0)
+		return err;
+
+	snd_pcm_hw_params_get_buffer_size_max(rec->hw_params, &buffer_max);
+	period_bytes = A52_FRAME_SIZE * 2 * rec->channels;
+	max_periods = buffer_max / A52_FRAME_SIZE;
+
+	if ((err = snd_pcm_ioplug_set_param_minmax(&rec->io, SND_PCM_IOPLUG_HW_PERIOD_BYTES,
+						   period_bytes, period_bytes)) < 0 ||
+	    (err = snd_pcm_ioplug_set_param_minmax(&rec->io, SND_PCM_IOPLUG_HW_PERIODS,
+						   2, max_periods)) < 0)
+		return err;
+
+	return 0;
+}
+
+SND_PCM_PLUGIN_DEFINE_FUNC(a52)
+{
+	snd_config_iterator_t i, next;
+	int err;
+	const char *card = NULL;
+	unsigned int rate = 48000;
+	unsigned int bitrate = 448;
+	unsigned int channels = 6;
+	snd_pcm_format_t format = SND_PCM_FORMAT_S16_LE;
+	char devstr[128];
+	struct a52_ctx *rec;
+	
+	if (stream != SND_PCM_STREAM_PLAYBACK) {
+		SNDERR("a52 is only for playback");
+		return -EINVAL;
+	}
+
+	snd_config_for_each(i, next, conf) {
+		snd_config_t *n = snd_config_iterator_entry(i);
+		const char *id;
+		if (snd_config_get_id(n, &id) < 0)
+			continue;
+		if (strcmp(id, "comment") == 0 || strcmp(id, "type") == 0)
+			continue;
+		if (strcmp(id, "card") == 0) {
+			if (snd_config_get_string(n, &card) < 0) {
+				SNDERR("Invalid type for %s", id);
+				return -EINVAL;
+			}
+			continue;
+		}
+		if (strcmp(id, "rate") == 0) {
+			long val;
+			if (snd_config_get_integer(n, &val) < 0) {
+				SNDERR("Invalid type for %s", id);
+				return -EINVAL;
+			}
+			rate = val;
+			if (rate != 44100 && rate != 48000) {
+				SNDERR("rate must be 44100 or 48000");
+				return -EINVAL;
+			}
+			continue;
+		}
+		if (strcmp(id, "bitrate") == 0) {
+			long val;
+			if (snd_config_get_integer(n, &val) < 0) {
+				SNDERR("Invalid type for %s", id);
+				return -EINVAL;
+			}
+			bitrate = val;
+			if (bitrate < 128 || bitrate > 1000) {
+				SNDERR("Invalid bitrate value %d", bitrate);
+				return -EINVAL;
+			}
+			continue;
+		}
+		if (strcmp(id, "channels") == 0) {
+			long val;
+			if (snd_config_get_integer(n, &val) < 0) {
+				SNDERR("Invalid type for %s", id);
+				return -EINVAL;
+			}
+			channels = val;
+			if (channels != 2 && channels != 4 && channels != 6) {
+				SNDERR("channels must be 2, 4 or 6");
+				return -EINVAL;
+			}
+			continue;
+		}
+		if (strcmp(id, "format") == 0) {
+			const char *str;
+			err = snd_config_get_string(n, &str);
+			if (err < 0) {
+				SNDERR("invalid type for %s", id);
+				return -EINVAL;
+			}
+			format = snd_pcm_format_value(str);
+			if (format == SND_PCM_FORMAT_UNKNOWN) {
+				SNDERR("unknown format %s", str);
+				return -EINVAL;
+			}
+			if (format != SND_PCM_FORMAT_S16_LE &&
+			    format != SND_PCM_FORMAT_S16_BE) {
+				SNDERR("Only S16_LE/BE formats are allowed");
+				return -EINVAL;
+			}
+			continue;
+		}
+		SNDERR("Unknown field %s", id);
+		return -EINVAL;
+	}
+
+	rec = calloc(1, sizeof(*rec));
+	if (! rec) {
+		SNDERR("cannot allocate");
+		return -ENOMEM;
+	}
+
+	rec->rate = rate;
+	rec->bitrate = bitrate;
+	rec->channels = channels;
+	rec->format = format;
+
+	avcodec_register_all();
+	rec->codec = avcodec_find_encoder(CODEC_ID_AC3);
+	if (! rec->codec) {
+		SNDERR("Cannot find codec engine");
+		err = -EINVAL;
+		goto error;
+	}
+
+	snprintf(devstr, sizeof(devstr),
+		 "plug:iec958:{AES0 0x%x AES1 0x%x AES2 0x%x AES3 0x%x %s%s}",
+		 IEC958_AES0_CON_EMPHASIS_NONE | IEC958_AES0_NONAUDIO |
+		 IEC958_AES0_CON_NOT_COPYRIGHT,
+		 IEC958_AES1_CON_ORIGINAL | IEC958_AES1_CON_PCM_CODER,
+		 0, rate == 48000 ? IEC958_AES3_CON_FS_48000 : IEC958_AES3_CON_FS_44100,
+		 card ? " CARD " : "",
+		 card ? card : "");
+
+	err = snd_pcm_open(&rec->slave, devstr, stream, mode);
+	if (err < 0)
+		goto error;
+
+	rec->io.version = SND_PCM_IOPLUG_VERSION;
+	rec->io.name = "A52 Output Plugin";
+	rec->io.mmap_rw = 0;
+	rec->io.callback = &a52_ops;
+	rec->io.private_data = rec;
+
+	err = snd_pcm_ioplug_create(&rec->io, name, stream, mode);
+	if (err < 0)
+		goto error;
+
+	if ((err = a52_set_hw_constraint(rec)) < 0) {
+		snd_pcm_ioplug_delete(&rec->io);
+		return err;
+	}
+
+	*pcmp = rec->io.pcm;
+	return 0;
+
+ error:
+	if (rec->slave)
+		snd_pcm_close(rec->slave);
+	free(rec);
+	return err;
+}
+
+SND_PCM_PLUGIN_SYMBOL(a52);