mp3dec: decode more data from Info header

Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavformat/avio_internal.h

@@ -94,6 +94,8 @@ void ffio_init_checksum(AVIOContext *s,
 unsigned long ffio_get_checksum(AVIOContext *s);
 unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
                                     unsigned int len);
+unsigned long ff_crcA001_update(unsigned long checksum, const uint8_t *buf,
+                                unsigned int len);
 
 /**
  * Open a write only packetized memory stream with a maximum packet

libavformat/aviobuf.c

@@ -414,6 +414,12 @@ unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
     return av_crc(av_crc_get_table(AV_CRC_32_IEEE), checksum, buf, len);
 }
 
+unsigned long ff_crcA001_update(unsigned long checksum, const uint8_t *buf,
+                                unsigned int len)
+{
+    return av_crc(av_crc_get_table(AV_CRC_16_ANSI_LE), checksum, buf, len);
+}
+
 unsigned long ffio_get_checksum(AVIOContext *s)
 {
     s->checksum = s->update_checksum(s->checksum, s->checksum_ptr,

libavformat/mp3dec.c

@@ -21,10 +21,12 @@
 
 #include "libavutil/avstring.h"
 #include "libavutil/intreadwrite.h"
+#include "libavutil/crc.h"
 #include "libavutil/dict.h"
 #include "libavutil/mathematics.h"
 #include "avformat.h"
 #include "internal.h"
+#include "avio_internal.h"
 #include "id3v2.h"
 #include "id3v1.h"
 #include "replaygain.h"
@@ -128,11 +130,20 @@ static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration
     mp3->xing_toc = 1;
 }
 
-
 static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
                                MPADecodeHeader *c, uint32_t spf)
 {
+#define LAST_BITS(k, n) ((k) & ((1 << (n)) - 1))
+#define MIDDLE_BITS(k, m, n) LAST_BITS((k) >> (m), ((n) - (m)))
+
+    uint16_t crc;
     uint32_t v;
+
+    char version[10];
+
+    uint32_t peak   = 0;
+    int32_t  r_gain = INT32_MIN, a_gain = INT32_MIN;
+
     MP3DecContext *mp3 = s->priv_data;
     const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
 
@@ -140,17 +151,87 @@ static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
     avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]);
     v = avio_rb32(s->pb);
     mp3->is_cbr = v == MKBETAG('I', 'n', 'f', 'o');
-    if (v == MKBETAG('X', 'i', 'n', 'g') || mp3->is_cbr) {
-        v = avio_rb32(s->pb);
-        if (v & XING_FLAG_FRAMES)
-            mp3->frames = avio_rb32(s->pb);
-        if (v & XING_FLAG_SIZE)
-            mp3->size = avio_rb32(s->pb);
-        if (v & XING_FLAG_TOC && mp3->frames)
-            read_xing_toc(s, mp3->size,
-                          av_rescale_q(mp3->frames,
+    if (v != MKBETAG('X', 'i', 'n', 'g') && !mp3->is_cbr)
+        return;
+
+    v = avio_rb32(s->pb);
+    if (v & XING_FLAG_FRAMES)
+        mp3->frames = avio_rb32(s->pb);
+    if (v & XING_FLAG_SIZE)
+        mp3->size = avio_rb32(s->pb);
+    if (v & XING_FLAG_TOC && mp3->frames)
+        read_xing_toc(s, mp3->size, av_rescale_q(mp3->frames,
                                        (AVRational){spf, c->sample_rate},
                                        st->time_base));
+
+    /* VBR quality */
+    avio_rb32(s->pb);
+
+    /* Encoder short version string */
+    memset(version, 0, sizeof(version));
+    avio_read(s->pb, version, 9);
+
+    /* Info Tag revision + VBR method */
+    avio_r8(s->pb);
+
+    /* Lowpass filter value */
+    avio_r8(s->pb);
+
+    /* ReplayGain peak */
+    v    = avio_rb32(s->pb);
+    peak = av_rescale(v, 100000, 1 << 23);
+
+    /* Radio ReplayGain */
+    v = avio_rb16(s->pb);
+
+    if (MIDDLE_BITS(v, 13, 15) == 1) {
+        r_gain = MIDDLE_BITS(v, 0, 8) * 10000;
+
+        if (v & (1 << 9))
+            r_gain *= -1;
+    }
+
+    /* Audiophile ReplayGain */
+    v = avio_rb16(s->pb);
+
+    if (MIDDLE_BITS(v, 13, 15) == 2) {
+        a_gain = MIDDLE_BITS(v, 0, 8) * 10000;
+
+        if (v & (1 << 9))
+            a_gain *= -1;
+    }
+
+    /* Encoding flags + ATH Type */
+    avio_r8(s->pb);
+
+    /* if ABR {specified bitrate} else {minimal bitrate} */
+    avio_r8(s->pb);
+
+    /* Encoder delays */
+    avio_rb24(s->pb);
+
+    /* Misc */
+    avio_r8(s->pb);
+
+    /* MP3 gain */
+    avio_r8(s->pb);
+
+    /* Preset and surround info */
+    avio_rb16(s->pb);
+
+    /* Music length */
+    avio_rb32(s->pb);
+
+    /* Music CRC */
+    avio_rb16(s->pb);
+
+    /* Info Tag CRC */
+    crc = ffio_get_checksum(s->pb);
+    v   = avio_rb16(s->pb);
+
+    if (v == crc) {
+        ff_replaygain_export_raw(st, r_gain, peak, a_gain, 0);
+        av_dict_set(&st->metadata, "encoder", version, 0);
     }
 }
 
@@ -183,6 +264,8 @@ static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
     int vbrtag_size = 0;
     MP3DecContext *mp3 = s->priv_data;
 
+    ffio_init_checksum(s->pb, ff_crcA001_update, 0);
+
     v = avio_rb32(s->pb);
     if(ff_mpa_check_header(v) < 0)
       return -1;