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-rw-r--r--Documentation/sound/alsa/compress_offload.txt46
-rw-r--r--include/sound/compress_driver.h8
-rw-r--r--include/uapi/sound/compress_offload.h31
-rw-r--r--sound/core/compress_offload.c96
4 files changed, 180 insertions, 1 deletions
diff --git a/Documentation/sound/alsa/compress_offload.txt b/Documentation/sound/alsa/compress_offload.txt
index 90e9b3a11abc..0bcc55155911 100644
--- a/Documentation/sound/alsa/compress_offload.txt
+++ b/Documentation/sound/alsa/compress_offload.txt
@@ -145,6 +145,52 @@ Modifications include:
- Addition of encoding options when required (derived from OpenMAX IL)
- Addition of rateControlSupported (missing in OpenMAX AL)
+Gapless Playback
+================
+When playing thru an album, the decoders have the ability to skip the encoder
+delay and padding and directly move from one track content to another. The end
+user can perceive this as gapless playback as we dont have silence while
+switching from one track to another
+
+Also, there might be low-intensity noises due to encoding. Perfect gapless is
+difficult to reach with all types of compressed data, but works fine with most
+music content. The decoder needs to know the encoder delay and encoder padding.
+So we need to pass this to DSP. This metadata is extracted from ID3/MP4 headers
+and are not present by default in the bitstream, hence the need for a new
+interface to pass this information to the DSP. Also DSP and userspace needs to
+switch from one track to another and start using data for second track.
+
+The main additions are:
+
+- set_metadata
+This routine sets the encoder delay and encoder padding. This can be used by
+decoder to strip the silence. This needs to be set before the data in the track
+is written.
+
+- set_next_track
+This routine tells DSP that metadata and write operation sent after this would
+correspond to subsequent track
+
+- partial drain
+This is called when end of file is reached. The userspace can inform DSP that
+EOF is reached and now DSP can start skipping padding delay. Also next write
+data would belong to next track
+
+Sequence flow for gapless would be:
+- Open
+- Get caps / codec caps
+- Set params
+- Set metadata of the first track
+- Fill data of the first track
+- Trigger start
+- User-space finished sending all,
+- Indicaite next track data by sending set_next_track
+- Set metadata of the next track
+- then call partial_drain to flush most of buffer in DSP
+- Fill data of the next track
+- DSP switches to second track
+(note: order for partial_drain and write for next track can be reversed as well)
+
Not supported:
- Support for VoIP/circuit-switched calls is not the target of this
diff --git a/include/sound/compress_driver.h b/include/sound/compress_driver.h
index f2912abacdf3..ff6c74153fa1 100644
--- a/include/sound/compress_driver.h
+++ b/include/sound/compress_driver.h
@@ -71,6 +71,8 @@ struct snd_compr_runtime {
* @runtime: pointer to runtime structure
* @device: device pointer
* @direction: stream direction, playback/recording
+ * @metadata_set: metadata set flag, true when set
+ * @next_track: has userspace signall next track transistion, true when set
* @private_data: pointer to DSP private data
*/
struct snd_compr_stream {
@@ -79,6 +81,8 @@ struct snd_compr_stream {
struct snd_compr_runtime *runtime;
struct snd_compr *device;
enum snd_compr_direction direction;
+ bool metadata_set;
+ bool next_track;
void *private_data;
};
@@ -110,6 +114,10 @@ struct snd_compr_ops {
struct snd_compr_params *params);
int (*get_params)(struct snd_compr_stream *stream,
struct snd_codec *params);
+ int (*set_metadata)(struct snd_compr_stream *stream,
+ struct snd_compr_metadata *metadata);
+ int (*get_metadata)(struct snd_compr_stream *stream,
+ struct snd_compr_metadata *metadata);
int (*trigger)(struct snd_compr_stream *stream, int cmd);
int (*pointer)(struct snd_compr_stream *stream,
struct snd_compr_tstamp *tstamp);
diff --git a/include/uapi/sound/compress_offload.h b/include/uapi/sound/compress_offload.h
index 05341a43fedf..d630163b9a2e 100644
--- a/include/uapi/sound/compress_offload.h
+++ b/include/uapi/sound/compress_offload.h
@@ -30,7 +30,7 @@
#include <sound/compress_params.h>
-#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 1, 0)
+#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 1, 1)
/**
* struct snd_compressed_buffer: compressed buffer
* @fragment_size: size of buffer fragment in bytes
@@ -122,6 +122,27 @@ struct snd_compr_codec_caps {
};
/**
+ * @SNDRV_COMPRESS_ENCODER_PADDING: no of samples appended by the encoder at the
+ * end of the track
+ * @SNDRV_COMPRESS_ENCODER_DELAY: no of samples inserted by the encoder at the
+ * beginning of the track
+ */
+enum {
+ SNDRV_COMPRESS_ENCODER_PADDING = 1,
+ SNDRV_COMPRESS_ENCODER_DELAY = 2,
+};
+
+/**
+ * struct snd_compr_metadata: compressed stream metadata
+ * @key: key id
+ * @value: key value
+ */
+struct snd_compr_metadata {
+ __u32 key;
+ __u32 value[8];
+};
+
+/**
* compress path ioctl definitions
* SNDRV_COMPRESS_GET_CAPS: Query capability of DSP
* SNDRV_COMPRESS_GET_CODEC_CAPS: Query capability of a codec
@@ -145,6 +166,10 @@ struct snd_compr_codec_caps {
struct snd_compr_codec_caps)
#define SNDRV_COMPRESS_SET_PARAMS _IOW('C', 0x12, struct snd_compr_params)
#define SNDRV_COMPRESS_GET_PARAMS _IOR('C', 0x13, struct snd_codec)
+#define SNDRV_COMPRESS_SET_METADATA _IOW('C', 0x14,\
+ struct snd_compr_metadata)
+#define SNDRV_COMPRESS_GET_METADATA _IOWR('C', 0x15,\
+ struct snd_compr_metadata)
#define SNDRV_COMPRESS_TSTAMP _IOR('C', 0x20, struct snd_compr_tstamp)
#define SNDRV_COMPRESS_AVAIL _IOR('C', 0x21, struct snd_compr_avail)
#define SNDRV_COMPRESS_PAUSE _IO('C', 0x30)
@@ -152,10 +177,14 @@ struct snd_compr_codec_caps {
#define SNDRV_COMPRESS_START _IO('C', 0x32)
#define SNDRV_COMPRESS_STOP _IO('C', 0x33)
#define SNDRV_COMPRESS_DRAIN _IO('C', 0x34)
+#define SNDRV_COMPRESS_NEXT_TRACK _IO('C', 0x35)
+#define SNDRV_COMPRESS_PARTIAL_DRAIN _IO('C', 0x36)
/*
* TODO
* 1. add mmap support
*
*/
#define SND_COMPR_TRIGGER_DRAIN 7 /*FIXME move this to pcm.h */
+#define SND_COMPR_TRIGGER_NEXT_TRACK 8
+#define SND_COMPR_TRIGGER_PARTIAL_DRAIN 9
#endif
diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index 2d620688cfb7..c84abc886e90 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -486,6 +486,8 @@ snd_compr_set_params(struct snd_compr_stream *stream, unsigned long arg)
if (retval)
goto out;
stream->runtime->state = SNDRV_PCM_STATE_SETUP;
+ stream->metadata_set = false;
+ stream->next_track = false;
} else {
return -EPERM;
}
@@ -517,6 +519,49 @@ out:
return retval;
}
+static int
+snd_compr_get_metadata(struct snd_compr_stream *stream, unsigned long arg)
+{
+ struct snd_compr_metadata metadata;
+ int retval;
+
+ if (!stream->ops->get_metadata)
+ return -ENXIO;
+
+ if (copy_from_user(&metadata, (void __user *)arg, sizeof(metadata)))
+ return -EFAULT;
+
+ retval = stream->ops->get_metadata(stream, &metadata);
+ if (retval != 0)
+ return retval;
+
+ if (copy_to_user((void __user *)arg, &metadata, sizeof(metadata)))
+ return -EFAULT;
+
+ return 0;
+}
+
+static int
+snd_compr_set_metadata(struct snd_compr_stream *stream, unsigned long arg)
+{
+ struct snd_compr_metadata metadata;
+ int retval;
+
+ if (!stream->ops->set_metadata)
+ return -ENXIO;
+ /*
+ * we should allow parameter change only when stream has been
+ * opened not in other cases
+ */
+ if (copy_from_user(&metadata, (void __user *)arg, sizeof(metadata)))
+ return -EFAULT;
+
+ retval = stream->ops->set_metadata(stream, &metadata);
+ stream->metadata_set = true;
+
+ return retval;
+}
+
static inline int
snd_compr_tstamp(struct snd_compr_stream *stream, unsigned long arg)
{
@@ -600,6 +645,44 @@ static int snd_compr_drain(struct snd_compr_stream *stream)
return retval;
}
+static int snd_compr_next_track(struct snd_compr_stream *stream)
+{
+ int retval;
+
+ /* only a running stream can transition to next track */
+ if (stream->runtime->state != SNDRV_PCM_STATE_RUNNING)
+ return -EPERM;
+
+ /* you can signal next track isf this is intended to be a gapless stream
+ * and current track metadata is set
+ */
+ if (stream->metadata_set == false)
+ return -EPERM;
+
+ retval = stream->ops->trigger(stream, SND_COMPR_TRIGGER_NEXT_TRACK);
+ if (retval != 0)
+ return retval;
+ stream->metadata_set = false;
+ stream->next_track = true;
+ return 0;
+}
+
+static int snd_compr_partial_drain(struct snd_compr_stream *stream)
+{
+ int retval;
+ if (stream->runtime->state == SNDRV_PCM_STATE_PREPARED ||
+ stream->runtime->state == SNDRV_PCM_STATE_SETUP)
+ return -EPERM;
+ /* stream can be drained only when next track has been signalled */
+ if (stream->next_track == false)
+ return -EPERM;
+
+ retval = stream->ops->trigger(stream, SND_COMPR_TRIGGER_PARTIAL_DRAIN);
+
+ stream->next_track = false;
+ return retval;
+}
+
static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
struct snd_compr_file *data = f->private_data;
@@ -629,6 +712,12 @@ static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
case _IOC_NR(SNDRV_COMPRESS_GET_PARAMS):
retval = snd_compr_get_params(stream, arg);
break;
+ case _IOC_NR(SNDRV_COMPRESS_SET_METADATA):
+ retval = snd_compr_set_metadata(stream, arg);
+ break;
+ case _IOC_NR(SNDRV_COMPRESS_GET_METADATA):
+ retval = snd_compr_get_metadata(stream, arg);
+ break;
case _IOC_NR(SNDRV_COMPRESS_TSTAMP):
retval = snd_compr_tstamp(stream, arg);
break;
@@ -650,6 +739,13 @@ static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
case _IOC_NR(SNDRV_COMPRESS_DRAIN):
retval = snd_compr_drain(stream);
break;
+ case _IOC_NR(SNDRV_COMPRESS_PARTIAL_DRAIN):
+ retval = snd_compr_partial_drain(stream);
+ break;
+ case _IOC_NR(SNDRV_COMPRESS_NEXT_TRACK):
+ retval = snd_compr_next_track(stream);
+ break;
+
}
mutex_unlock(&stream->device->lock);
return retval;