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authorJ. Alexander Treuman <jat@spatialrift.net>2006-07-25 22:49:10 +0000
committerJ. Alexander Treuman <jat@spatialrift.net>2006-07-25 22:49:10 +0000
commit1523e8a84290690e67474534a99a250be47d751b (patch)
tree12de7eff08ed1ff9f6e2a405923f208d811fe417 /src/inputPlugins/mp3_plugin.c
parenta686436c771c21d44b7ae80e9e4d0bb6a6d413d9 (diff)
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Parse lame tag for encoder delay/padding so we can later implement gapless
git-svn-id: https://svn.musicpd.org/mpd/trunk@4460 09075e82-0dd4-0310-85a5-a0d7c8717e4f
Diffstat (limited to '')
-rw-r--r--src/inputPlugins/mp3_plugin.c67
1 files changed, 67 insertions, 0 deletions
diff --git a/src/inputPlugins/mp3_plugin.c b/src/inputPlugins/mp3_plugin.c
index 90c3f6172..549e62af3 100644
--- a/src/inputPlugins/mp3_plugin.c
+++ b/src/inputPlugins/mp3_plugin.c
@@ -455,6 +455,18 @@ enum {
XING_SCALE = 0x00000008L,
};
+struct lame {
+ char encoder[10]; /* 9 byte encoder name/version ("LAME3.97b") */
+#if 0
+ /* See related comment in parse_lame() */
+ float peak; /* replaygain peak */
+ float trackGain; /* replaygain track gain */
+ float albumGain; /* replaygain album gain */
+#endif
+ int encoderDelay; /* # of added samples at start of mp3 */
+ int encoderPadding; /* # of added samples at end of mp3 */
+};
+
static int parse_xing(struct xing *xing, struct mad_bitptr *ptr, int *oldbitlen)
{
unsigned long bits;
@@ -528,13 +540,67 @@ static int parse_xing(struct xing *xing, struct mad_bitptr *ptr, int *oldbitlen)
return 0;
}
+static int parse_lame(struct lame *lame, struct mad_bitptr *ptr, int *bitlen)
+{
+ int i;
+
+ /* Unlike the xing header, the lame tag has a fixed length. Fail if
+ * not all 36 bytes (288 bits) are there. */
+ if (*bitlen < 288) return 0;
+
+ for (i = 0; i < 9; i++) lame->encoder[i] = (char)mad_bit_read(ptr, 8);
+ lame->encoder[9] = '\0';
+
+ /* This is technically incorrect, since the encoder might not be lame.
+ * But there's no other way to determine if this is a lame tag, and we
+ * wouldn't want to go reading a tag that's not there. */
+ if (strncmp(lame->encoder, "LAME", 4) != 0) return 0;
+
+#if 0
+ /* Apparently lame versions <3.97b1 do not calculate replaygain. I'm
+ * using lame 3.97b2, and while it does calculate replaygain, it's
+ * setting the values to 0. Using --replaygain-(fast|accurate) doesn't
+ * make any difference. Leaving this code unused until we have a way
+ * of testing it. -- jat */
+
+ mad_bit_read(ptr, 16);
+
+ mad_bit_read(ptr, 32); /* peak */
+
+ mad_bit_read(ptr, 6); /* header */
+ bits = mad_bit_read(ptr, 1); /* sign bit */
+ lame->trackGain = mad_bit_read(ptr, 9); /* gain*10 */
+ lame->trackGain = (bits ? -lame->trackGain : lame->trackGain) / 10;
+
+ mad_bit_read(ptr, 6); /* header */
+ bits = mad_bit_read(ptr, 1); /* sign bit */
+ lame->albumGain = mad_bit_read(ptr, 9); /* gain*10 */
+ lame->albumGain = (bits ? -lame->albumGain : lame->albumGain) / 10;
+
+ mad_bit_read(ptr, 16);
+#else
+ mad_bit_read(ptr, 96);
+#endif
+
+ lame->encoderDelay = mad_bit_read(ptr, 12);
+ lame->encoderPadding = mad_bit_read(ptr, 12);
+
+ mad_bit_read(ptr, 96);
+
+ *bitlen -= 288;
+
+ return 1;
+}
+
static int decodeFirstFrame(mp3DecodeData * data, DecoderControl * dc,
MpdTag ** tag, ReplayGainInfo ** replayGainInfo)
{
struct xing xing;
+ struct lame lame;
struct mad_bitptr ptr;
int bitlen;
int found_xing;
+ int found_lame;
int ret;
int skip;
@@ -557,6 +623,7 @@ static int decodeFirstFrame(mp3DecodeData * data, DecoderControl * dc,
bitlen = data->stream.anc_bitlen;
found_xing = parse_xing(&xing, &ptr, &bitlen);
+ found_lame = (found_xing ? parse_lame(&lame, &ptr, &bitlen) : 0);
if (found_xing) {
if (xing.flags & XING_FRAMES) {