[FFmpeg-devel] [PATCH v2 4/5] avutil/channel_layout: add av_channel_layout_retype()
Marton Balint
cus at passwd.hu
Sun Feb 4 21:28:11 EET 2024
Signed-off-by: Marton Balint <cus at passwd.hu>
---
doc/APIchanges | 3 ++
libavutil/channel_layout.c | 106 +++++++++++++++++++++++++++++++++++++
libavutil/channel_layout.h | 40 ++++++++++++++
libavutil/version.h | 2 +-
4 files changed, 150 insertions(+), 1 deletion(-)
diff --git a/doc/APIchanges b/doc/APIchanges
index cdb9b6a458..221fea30c2 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2023-02-09
API changes, most recent first:
+2024-02-xx - xxxxxxxxxx - lavu 58.38.100 - channel_layout.h
+ Add av_channel_layout_retype().
+
2024-02-xx - xxxxxxxxxx - lavu 58.37.100 - channel_layout.h
Add av_channel_layout_custom_init().
diff --git a/libavutil/channel_layout.c b/libavutil/channel_layout.c
index 40e31e9d12..7f51c076dc 100644
--- a/libavutil/channel_layout.c
+++ b/libavutil/channel_layout.c
@@ -1036,3 +1036,109 @@ uint64_t av_channel_layout_subset(const AVChannelLayout *channel_layout,
return ret;
}
+
+static int64_t masked_description(AVChannelLayout *channel_layout, int start_channel)
+{
+ uint64_t mask = 0;
+ for (int i = start_channel; i < channel_layout->nb_channels; i++) {
+ enum AVChannel ch = channel_layout->u.map[i].id;
+ if (ch >= 0 && ch < 63 && mask < (1ULL << ch))
+ mask |= (1ULL << ch);
+ else
+ return AVERROR(EINVAL);
+ }
+ return mask;
+}
+
+static int has_channel_names(AVChannelLayout *channel_layout)
+{
+ if (channel_layout->order != AV_CHANNEL_ORDER_CUSTOM)
+ return 0;
+ for (int i = 0; i < channel_layout->nb_channels; i++)
+ if (channel_layout->u.map[i].name[0])
+ return 1;
+ return 0;
+}
+
+int av_channel_layout_retype(AVChannelLayout *channel_layout, enum AVChannelOrder order, int flags)
+{
+ int allow_lossy = !(flags & AV_CHANNEL_LAYOUT_RETYPE_FLAG_LOSSLESS);
+ int lossy;
+
+ if (!av_channel_layout_check(channel_layout))
+ return AVERROR(EINVAL);
+
+ if (channel_layout->order == order)
+ return 0;
+
+ switch (order) {
+ case AV_CHANNEL_ORDER_UNSPEC: {
+ int nb_channels = channel_layout->nb_channels;
+ if (channel_layout->order == AV_CHANNEL_ORDER_CUSTOM) {
+ lossy = 0;
+ for (int i = 0; i < nb_channels; i++) {
+ if (channel_layout->u.map[i].id != AV_CHAN_UNKNOWN || channel_layout->u.map[i].name[0]) {
+ lossy = 1;
+ break;
+ }
+ }
+ } else {
+ lossy = 1;
+ }
+ if (!lossy || allow_lossy) {
+ av_channel_layout_uninit(channel_layout);
+ channel_layout->order = AV_CHANNEL_ORDER_UNSPEC;
+ channel_layout->nb_channels = nb_channels;
+ return lossy;
+ }
+ return AVERROR(ENOSYS);
+ }
+ case AV_CHANNEL_ORDER_NATIVE:
+ if (channel_layout->order == AV_CHANNEL_ORDER_CUSTOM) {
+ int64_t mask = masked_description(channel_layout, 0);
+ if (mask < 0)
+ return AVERROR(ENOSYS);
+ lossy = has_channel_names(channel_layout);
+ if (!lossy || allow_lossy) {
+ av_channel_layout_uninit(channel_layout);
+ av_channel_layout_from_mask(channel_layout, mask);
+ return lossy;
+ }
+ }
+ return AVERROR(ENOSYS);
+ case AV_CHANNEL_ORDER_CUSTOM: {
+ AVChannelLayout custom = { 0 };
+ int ret = av_channel_layout_custom_init(&custom, channel_layout->nb_channels);
+ if (ret < 0)
+ return ret;
+ if (channel_layout->order != AV_CHANNEL_ORDER_UNSPEC)
+ for (int i = 0; i < channel_layout->nb_channels; i++)
+ custom.u.map[i].id = av_channel_layout_channel_from_index(channel_layout, i);
+ av_channel_layout_uninit(channel_layout);
+ *channel_layout = custom;
+ return 0;
+ }
+ case AV_CHANNEL_ORDER_AMBISONIC:
+ if (channel_layout->order == AV_CHANNEL_ORDER_CUSTOM) {
+ int64_t mask;
+ int nb_channels = channel_layout->nb_channels;
+ int order = ambisonic_order(channel_layout);
+ if (order < 0)
+ return AVERROR(ENOSYS);
+ mask = masked_description(channel_layout, (order + 1) * (order + 1));
+ if (mask < 0)
+ return AVERROR(ENOSYS);
+ lossy = has_channel_names(channel_layout);
+ if (!lossy || allow_lossy) {
+ av_channel_layout_uninit(channel_layout);
+ channel_layout->order = AV_CHANNEL_ORDER_AMBISONIC;
+ channel_layout->nb_channels = nb_channels;
+ channel_layout->u.mask = mask;
+ return lossy;
+ }
+ }
+ return AVERROR(ENOSYS);
+ default:
+ return AVERROR(EINVAL);
+ }
+}
diff --git a/libavutil/channel_layout.h b/libavutil/channel_layout.h
index dcc320cbfe..10260d3ec5 100644
--- a/libavutil/channel_layout.h
+++ b/libavutil/channel_layout.h
@@ -821,6 +821,46 @@ int av_channel_layout_check(const AVChannelLayout *channel_layout);
*/
int av_channel_layout_compare(const AVChannelLayout *chl, const AVChannelLayout *chl1);
+/**
+ * The conversion must be lossless.
+ */
+#define AV_CHANNEL_LAYOUT_RETYPE_FLAG_LOSSLESS (1 << 0)
+
+/**
+ * Change the AVChannelOrder of a channel layout.
+ *
+ * Change of AVChannelOrder can be either lossless or lossy. In case of a
+ * lossless conversion all the channel designations and the associated channel
+ * names (if any) are kept. On a lossy conversion the channel names and channel
+ * designations might be lost depending on the capabilities of the desired
+ * AVChannelOrder. Note that some conversions are simply not possible in which
+ * case this function returns AVERROR(ENOSYS).
+ *
+ * The following conversions are supported:
+ *
+ * Any -> Custom : Always possible, always lossless.
+ * Any -> Unspecified: Always possible, lossless if channel designations
+ * are all unknown and channel names are not used, lossy otherwise.
+ * Custom -> Ambisonic : Possible if it contains ambisonic channels with
+ * optional non-diegetic channels in the end. Lossy if the channels have
+ * custom names, lossless otherwise.
+ * Custom -> Native : Possible if it contains native channels in native
+ * order. Lossy if the channels have custom names, lossless otherwise.
+ *
+ * On error this function keeps the original channel layout untouched.
+ *
+ * @param channel_layout channel layout which will be changed
+ * @param order the desired channel layout order
+ * @param flags a combination of AV_CHANNEL_LAYOUT_RETYPE_FLAG_* constants
+ * @return 0 if the conversion was successful and lossless or if the channel
+ * layout was already in the desired order
+ * 1 if the conversion was successful but lossy
+ * AVERROR(ENOSYS) if the conversion was not possible (or would be
+ * lossy and AV_CHANNEL_LAYOUT_RETYPE_FLAG_LOSSLESS was specified)
+ * AVERROR(EINVAL), AVERROR(ENOMEM) on error
+ */
+int av_channel_layout_retype(AVChannelLayout *channel_layout, enum AVChannelOrder order, int flags);
+
/**
* @}
*/
diff --git a/libavutil/version.h b/libavutil/version.h
index 3b38f8f5da..cebf4a0acd 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,7 +79,7 @@
*/
#define LIBAVUTIL_VERSION_MAJOR 58
-#define LIBAVUTIL_VERSION_MINOR 37
+#define LIBAVUTIL_VERSION_MINOR 38
#define LIBAVUTIL_VERSION_MICRO 100
#define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
--
2.35.3
More information about the ffmpeg-devel
mailing list