audio: confine demux_mkv audio PCM hack

Let codec_tags.c do the messy mapping.

In theory we could simplify further by makign demux_mkv.c directly use
codec names instead of the MPlayer-inherited "internal FourCC" business,
but I'd rather not touch this - it would just break things.

audio/decode/ad_lavc.c

@@ -71,50 +71,6 @@ const struct m_sub_options ad_lavc_conf = {
     },
 };
 
-struct pcm_map
-{
-    int tag;
-    const char *codecs[6]; // {any, 1byte, 2bytes, 3bytes, 4bytes, 8bytes}
-};
-
-// NOTE: these are needed to make rawaudio with demux_mkv work.
-static const struct pcm_map tag_map[] = {
-    // Microsoft PCM
-    {0x0,           {NULL, "pcm_u8", "pcm_s16le", "pcm_s24le", "pcm_s32le"}},
-    {0x1,           {NULL, "pcm_u8", "pcm_s16le", "pcm_s24le", "pcm_s32le"}},
-    // MS PCM, Extended
-    {0xfffe,        {NULL, "pcm_u8", "pcm_s16le", "pcm_s24le", "pcm_s32le"}},
-    // IEEE float
-    {0x3,           {"pcm_f32le", [5] = "pcm_f64le"}},
-    // 'raw '
-    {0x20776172,    {"pcm_s16be", [1] = "pcm_u8"}},
-    // 'twos', used by demux_mkv.c internally
-    {MKTAG('t', 'w', 'o', 's'),
-                    {NULL, "pcm_s8", "pcm_s16be", "pcm_s24be", "pcm_s32be"}},
-    {-1},
-};
-
-static const char *find_pcm_decoder(const struct pcm_map *map, int format,
-                                    int bits_per_sample)
-{
-    int bytes = (bits_per_sample + 7) / 8;
-    if (bytes == 8)
-        bytes = 5; // 64 bit entry
-    for (int n = 0; map[n].tag != -1; n++) {
-        const struct pcm_map *entry = &map[n];
-        if (entry->tag == format) {
-            const char *dec = NULL;
-            if (bytes >= 1 && bytes <= 5)
-                dec = entry->codecs[bytes];
-            if (!dec)
-                dec = entry->codecs[0];
-            if (dec)
-                return dec;
-        }
-    }
-    return NULL;
-}
-
 static void set_data_from_avframe(struct dec_audio *da)
 {
     struct priv *priv = da->priv;
@@ -170,11 +126,6 @@ static int init(struct dec_audio *da, const char *decoder)
     struct priv *ctx = talloc_zero(NULL, struct priv);
     da->priv = ctx;
 
-    if (sh_audio->wf && strcmp(decoder, "pcm") == 0) {
-        decoder = find_pcm_decoder(tag_map, sh->format,
-                                   sh_audio->wf->wBitsPerSample);
-    }
-
     ctx->force_channel_map = sh_audio->force_channels;
 
     lavc_codec = avcodec_find_decoder_by_name(decoder);
@@ -336,7 +287,6 @@ static int decode_packet(struct dec_audio *da)
 static void add_decoders(struct mp_decoder_list *list)
 {
     mp_add_lavc_decoders(list, AVMEDIA_TYPE_AUDIO);
-    mp_add_decoder(list, "lavc", "pcm", "pcm", "Raw PCM");
 }
 
 const struct ad_functions ad_lavc = {

demux/codec_tags.c

@@ -97,12 +97,6 @@ static const struct mp_codec_tag mp_audio_codec_tags[] = {
     {MKTAG('s', 'a', 'm', 'r'), "amr_nb"},
     {MKTAG('s', 'a', 'w', 'b'), "amr_wb"},
     {MKTAG('v', 'r', 'b', 's'), "vorbis"},
-    // Special cased in ad_lavc:
-    {0                        , "pcm"},
-    {0x1                      , "pcm"}, // lavf: pcm_s16le
-    {0x3                      , "pcm"}, // lavf: pcm_f32le
-    {0xfffe                   , "pcm"},
-    {MKTAG('t', 'w', 'o', 's'), "pcm"},
     // ------- internal mplayer FourCCs ------
     {MKTAG('O', 'p', 'u', 's'), "opus"}, // demux_mkv.c
     {MKTAG('a', 'L', 'a', 'C'), "alac"}, // demux_mkv.c
@@ -358,6 +352,28 @@ static const char *lookup_tag(const struct mp_codec_tag *mp_table,
     return id == AV_CODEC_ID_NONE ? NULL : mp_codec_from_av_codec_id(id);
 }
 
+static const char *pcm_le[] = {"pcm_u8", "pcm_s16le", "pcm_s24le", "pcm_s32le"};
+static const char *pcm_be[] = {"pcm_s8", "pcm_s16be", "pcm_s24be", "pcm_s32be"};
+
+static const char *map_audio_pcm_tag(uint32_t tag, int bits)
+{
+    int bytes = (bits + 7) / 8;
+    switch (tag) {
+    case 0x0:       // Microsoft PCM
+    case 0x1:
+    case 0xfffe:    // MS PCM, Extended
+        return bytes >= 1 && bytes <= 4 ? pcm_le[bytes - 1] : NULL;
+    case 0x3:       // IEEE float
+        return bits == 64 ? "pcm_f64le" : "pcm_f32le";
+    case 0x20776172:// 'raw '
+        return bits == 8 ? "pcm_u8" : "pcm_s16be";
+    case MKTAG('t', 'w', 'o', 's'): // demux_mkv.c internal
+        return bytes >= 1 && bytes <= 4 ? pcm_be[bytes - 1] : NULL;
+    default:
+        return NULL;
+    }
+}
+
 void mp_set_codec_from_tag(struct sh_stream *sh)
 {
     switch (sh->type) {
@@ -370,6 +386,12 @@ void mp_set_codec_from_tag(struct sh_stream *sh)
         sh->codec = lookup_tag(mp_audio_codec_tags,
                                avformat_get_riff_audio_tags(),
                                sh->format);
+        if (sh->audio && sh->audio->wf) {
+            const char *codec =
+                map_audio_pcm_tag(sh->format, sh->audio->wf->wBitsPerSample);
+            if (codec)
+                sh->codec = codec;
+        }
         break;
     default: ;
     }