avutil/samplefmt: add AV_SAMPLE_FMT_DSD

DSD (Direct Stream Digital) is one-bit sigma-delta modulated audio,
found on Super Audio CDs and in DSF/DSDIFF files. libavcodec has
several decoders producing it internally (dsd_*, dst, wavpack DSD),
each converting to float PCM as part of decoding, which makes the
bitstream itself inaccessible to API users.

Add a dedicated sample format so raw DSD can be carried through the
pipeline, e.g. for bit-perfect pass-through to DSD capable DACs.

The format has no planar variant, altform references itself.

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>

doc/APIchanges

@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2026-06-23.
 
 API changes, most recent first:
 
+2026-09-xx - xxxxxxxxxx - lavu 61.7.100 - samplefmt.h
+  Add AV_SAMPLE_FMT_DSD.
+
 2026-09-01 - xxxxxxxxxx - lavc 63.10.100 - avcodec.h
   Add AVCodecContext.skip_pred.
 

libavutil/samplefmt.c

@@ -46,6 +46,7 @@ static const SampleFmtInfo sample_fmt_info[AV_SAMPLE_FMT_NB] = {
     [AV_SAMPLE_FMT_S64P] = { .name = "s64p", .bits = 64, .planar = 1, .altform = AV_SAMPLE_FMT_S64  },
     [AV_SAMPLE_FMT_FLTP] = { .name = "fltp", .bits = 32, .planar = 1, .altform = AV_SAMPLE_FMT_FLT  },
     [AV_SAMPLE_FMT_DBLP] = { .name = "dblp", .bits = 64, .planar = 1, .altform = AV_SAMPLE_FMT_DBL  },
+    [AV_SAMPLE_FMT_DSD]  = { .name =  "dsd", .bits =  8, .planar = 0, .altform = AV_SAMPLE_FMT_DSD  },
 };
 
 const char *av_get_sample_fmt_name(enum AVSampleFormat sample_fmt)
@@ -250,9 +251,14 @@ int av_samples_set_silence(uint8_t * const *audio_data, int offset, int nb_sampl
     int planes      = planar ? nb_channels : 1;
     int block_align = av_get_bytes_per_sample(sample_fmt) * (planar ? 1 : nb_channels);
     int data_size   = nb_samples * block_align;
-    int fill_char   = (sample_fmt == AV_SAMPLE_FMT_U8 ||
-                     sample_fmt == AV_SAMPLE_FMT_U8P) ? 0x80 : 0x00;
-    int i;
+    int fill_char, i;
+
+    if (sample_fmt == AV_SAMPLE_FMT_U8 || sample_fmt == AV_SAMPLE_FMT_U8P)
+        fill_char = 0x80;
+    else if (sample_fmt == AV_SAMPLE_FMT_DSD)
+        fill_char = 0x69; // only ultrasonic tones, filtered out on playback
+    else
+        fill_char = 0x00;
 
     offset *= block_align;
 

libavutil/samplefmt.h

@@ -68,6 +68,14 @@ enum AVSampleFormat {
     AV_SAMPLE_FMT_S64,         ///< signed 64 bits
     AV_SAMPLE_FMT_S64P,        ///< signed 64 bits, planar
 
+    /**
+     * DSD (Direct Stream Digital) bitstream, interleaved. Each byte
+     * carries 8 consecutive one-bit samples, most significant bit first.
+     * One sample in the API sense is one such byte, so the sample rate
+     * is 1/8th of the DSD bit rate.
+     */
+    AV_SAMPLE_FMT_DSD,
+
     AV_SAMPLE_FMT_NB           ///< Number of sample formats. DO NOT USE if linking dynamically
 };
 

libavutil/version.h

@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  61
-#define LIBAVUTIL_VERSION_MINOR   6
+#define LIBAVUTIL_VERSION_MINOR   7
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \

tests/ref/fate/samplefmt

@@ -11,6 +11,7 @@ Testing name/format round-trip
  9: name=dblp  roundtrip=OK
 10: name=s64   roundtrip=OK
 11: name=s64p  roundtrip=OK
+12: name=dsd   roundtrip=OK
 NONE name: (null)
 NB name: (null)
 unknown: -1
@@ -28,6 +29,7 @@ fltp: 4
 dblp: 8
 s64: 8
 s64p: 8
+dsd: 1
 NONE: 0
 
 Testing av_sample_fmt_is_planar()
@@ -43,6 +45,7 @@ fltp: 1
 dblp: 1
 s64: 0
 s64p: 1
+dsd: 0
 NONE: 0
 
 Testing packed/planar conversions
@@ -58,6 +61,7 @@ fltp: packed=flt  planar=fltp
 dblp: packed=dbl  planar=dblp
 s64: packed=s64  planar=s64p
 s64p: packed=s64  planar=s64p
+dsd: packed=dsd  planar=dsd
 
 Testing av_get_alt_sample_fmt()
 u8: alt_packed=u8   alt_planar=u8p
@@ -72,6 +76,7 @@ fltp: alt_packed=flt  alt_planar=fltp
 dblp: alt_packed=dbl  alt_planar=dblp
 s64: alt_packed=s64  alt_planar=s64p
 s64p: alt_packed=s64  alt_planar=s64p
+dsd: alt_packed=dsd  alt_planar=dsd
 
 Testing av_get_sample_fmt_string()
 header: name   depth
@@ -87,6 +92,7 @@ fltp     32
 dblp     64 
 s64      64 
 s64p     64 
+dsd       8 
 
 Testing av_samples_get_buffer_size()
 2ch 1024smp s16: 4096