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.

3 files changed, 48 insertions, 13 deletions

diff --git a/audio/decode/ad_spdif.c b/audio/decode/ad_spdif.c
index 60aef3b18f..30c7883bf4 100644
--- a/audio/decode/ad_spdif.c
+++ b/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,
diff --git a/audio/decode/dec_audio.c b/audio/decode/dec_audio.c
index 39e867cf42..c98d42f556 100644
--- a/audio/decode/dec_audio.c
+++ b/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;
 }
 
diff --git a/audio/decode/dec_audio.h b/audio/decode/dec_audio.h
index 7bc8b00b0f..ebe7c8ae5b 100644
--- a/audio/decode/dec_audio.h
+++ b/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 */