audio: change how spdif codecs are selected

Remove ad_spdif from the normal codec list, and select it explicitly.

One goal was to decouple this from the normal codec selection, so
they're less entangled and the decoder selection code can be simplified
in the far future. This means spdif codec selection is now done
explicitly via select_spdif_codec(). We can also remove the weird
requirements on "dts" and "dts-hd" for the --audio-spdif option, and it
can just do the right thing.

Now both video and audio codecs consist of a single codec family each,
vd_lavc and ad_lavc.

DOCS/interface-changes.rst

@@ -43,6 +43,8 @@ Interface changes
         - --sub-codepage=<codepage> does not force the codepage anymore
           (this requires different and new syntax)
     - remove --fs-black-out-screens option for macOS
+    - change how spdif codecs are selected. You can't enable spdif passthrough
+      with --ad anymore. This was deprecated; use --audio-spdif instead.
  --- mpv 0.22.0 ---
     - the "audio-device-list" property now sets empty device description to the
       device name as a fallback

DOCS/man/options.rst

@@ -1121,11 +1121,10 @@ Audio
     Possible codecs are ``ac3``, ``dts``, ``dts-hd``. Multiple codecs can be
     specified by separating them with ``,``. ``dts`` refers to low bitrate DTS
     core, while ``dts-hd`` refers to DTS MA (receiver and OS support varies).
-    You should only use either ``dts`` or ``dts-hd`` (if both are specified,
-    and ``dts`` comes first, only ``dts`` will be used).
+    If both ``dts`` and ``dts-hd`` are specified, it behaves equivalent to
+    specifying ``dts-hd`` only.
 
-    In general, all codecs in the ``spdif`` family listed with ``--ad=help``
-    are supported in theory.
+    In earlier mpv versions
 
     .. admonition:: Warning
 

audio/decode/ad_spdif.c

@@ -83,12 +83,10 @@ static int init(struct dec_audio *da, const char *decoder)
     spdif_ctx->use_dts_hd = da->opts->dtshd;
     spdif_ctx->pool = mp_audio_pool_create(spdif_ctx);
 
-    if (strcmp(decoder, "dts-hd") == 0) {
-        decoder = "dts";
+    if (strcmp(decoder, "spdif_dts_hd") == 0)
         spdif_ctx->use_dts_hd = true;
-    }
 
-    spdif_ctx->codec_id = mp_codec_to_av_codec_id(decoder);
+    spdif_ctx->codec_id = mp_codec_to_av_codec_id(da->codec->codec);
     return spdif_ctx->codec_id != AV_CODEC_ID_NONE;
 }
 
@@ -296,22 +294,53 @@ static const int codecs[] = {
     AV_CODEC_ID_NONE
 };
 
-static void add_decoders(struct mp_decoder_list *list)
+static bool find_codec(const char *name)
 {
     for (int n = 0; codecs[n] != AV_CODEC_ID_NONE; n++) {
         const char *format = mp_codec_from_av_codec_id(codecs[n]);
-        if (format) {
-            mp_add_decoder(list, "spdif", format, format,
-                           "libavformat/spdifenc audio pass-through decoder");
+        if (format && name && strcmp(format, name) == 0)
+            return true;
+    }
+    return false;
+}
+
+// codec is the libavcodec name of the source audio codec.
+// pref is a ","-separated list of names, some of them which do not match with
+// libavcodec names (like dts-hd).
+struct mp_decoder_list *select_spdif_codec(const char *codec, const char *pref)
+{
+    struct mp_decoder_list *list = talloc_zero(NULL, struct mp_decoder_list);
+
+    if (!find_codec(codec))
+        return list;
+
+    bool spdif_allowed = false, dts_hd_allowed = false;
+    bstr sel = bstr0(pref);
+    while (sel.len) {
+        bstr decoder;
+        bstr_split_tok(sel, ",", &decoder, &sel);
+        if (decoder.len) {
+            if (bstr_equals0(decoder, codec))
+                spdif_allowed = true;
+            if (bstr_equals0(decoder, "dts-hd") && strcmp(codec, "dts") == 0)
+                spdif_allowed = dts_hd_allowed = true;
         }
     }
-    mp_add_decoder(list, "spdif", "dts", "dts-hd",
+
+    if (!spdif_allowed)
+        return list;
+
+    const char *suffix_name = dts_hd_allowed ? "dts_hd" : codec;
+    char name[80];
+    snprintf(name, sizeof(name), "spdif_%s", suffix_name);
+    mp_add_decoder(list, "spdif", codec, name,
                    "libavformat/spdifenc audio pass-through decoder");
+    return list;
 }
 
 const struct ad_functions ad_spdif = {
     .name = "spdif",
-    .add_decoders = add_decoders,
+    .add_decoders = NULL,
     .init = init,
     .uninit = uninit,
     .control = control,

audio/decode/dec_audio.c

@@ -43,11 +43,12 @@
 #include "audio/filter/af.h"
 
 extern const struct ad_functions ad_lavc;
+
+// Not a real codec - specially treated.
 extern const struct ad_functions ad_spdif;
 
 static const struct ad_functions * const ad_drivers[] = {
     &ad_lavc,
-    &ad_spdif,
     NULL
 };
 
@@ -91,9 +92,9 @@ static struct mp_decoder_list *audio_select_decoders(struct dec_audio *d_audio)
     struct mp_decoder_list *list = audio_decoder_list();
     struct mp_decoder_list *new =
         mp_select_decoders(list, codec, opts->audio_decoders);
-    if (d_audio->try_spdif) {
+    if (d_audio->try_spdif && codec) {
         struct mp_decoder_list *spdif =
-            mp_select_decoder_list(list, codec, "spdif", opts->audio_spdif);
+            select_spdif_codec(codec, opts->audio_spdif);
         mp_append_decoders(spdif, new);
         talloc_free(new);
         new = spdif;
@@ -108,6 +109,8 @@ static const struct ad_functions *find_driver(const char *name)
         if (strcmp(ad_drivers[i]->name, name) == 0)
             return ad_drivers[i];
     }
+    if (strcmp(name, "spdif") == 0)
+        return &ad_spdif;
     return NULL;
 }
 

audio/decode/dec_audio.h

@@ -59,4 +59,7 @@ int audio_get_frame(struct dec_audio *d_audio, struct mp_audio **out_frame);
 
 void audio_reset_decoding(struct dec_audio *d_audio);
 
+// ad_spdif.c
+struct mp_decoder_list *select_spdif_codec(const char *codec, const char *pref);
+
 #endif /* MPLAYER_DEC_AUDIO_H */

common/codecs.c

@@ -130,22 +130,6 @@ struct mp_decoder_list *mp_select_decoders(struct mp_decoder_list *all,
     return list;
 }
 
-// selection is a ","-separated list of decoders, all in the given family.
-struct mp_decoder_list *mp_select_decoder_list(struct mp_decoder_list *all,
-                                               const char *codec,
-                                               const char *family,
-                                               const char *selection)
-{
-    struct mp_decoder_list *list = talloc_zero(NULL, struct mp_decoder_list);
-    bstr sel = bstr0(selection);
-    while (sel.len) {
-        bstr decoder;
-        bstr_split_tok(sel, ",", &decoder, &sel);
-        add_new(list, find_decoder(all, bstr0(family), decoder), codec);
-    }
-    return list;
-}
-
 void mp_append_decoders(struct mp_decoder_list *list, struct mp_decoder_list *a)
 {
     for (int n = 0; n < a->num_entries; n++)

common/codecs.h

@@ -37,11 +37,6 @@ struct mp_decoder_list *mp_select_decoders(struct mp_decoder_list *all,
                                            const char *codec,
                                            const char *selection);
 
-struct mp_decoder_list *mp_select_decoder_list(struct mp_decoder_list *all,
-                                               const char *codec,
-                                               const char *family,
-                                               const char *selection);
-
 void mp_append_decoders(struct mp_decoder_list *list, struct mp_decoder_list *a);
 
 struct mp_log;

options/options.c

@@ -804,7 +804,7 @@ const struct MPOpts mp_default_opts = {
     .use_terminal = 1,
     .msg_color = 1,
     .audio_driver_list = NULL,
-    .audio_decoders = "-spdif:*", // never select spdif by default
+    .audio_decoders = NULL,
     .video_decoders = NULL,
     .deinterlace = -1,
     .softvol = SOFTVOL_AUTO,