inputPlugins/mp3_plugin: parse LAME tags for ReplayGain info
Parse ReplayGain info in LAME tags and use it if no ID3v2 ReplayGain tags are found. This is currently a bit unsafe, as apparently some LAME tags have bogus ReplayGain values. But I'm finding a lot of MP3s with valid LAME tags that fail the LAME tag CRC check. So until I figure out why that's happening, it's an unreliable method for checking if the LAME tag is valid. A big thanks to tmz for writing the original patch. git-svn-id: https://svn.musicpd.org/mpd/trunk@6798 09075e82-0dd4-0310-85a5-a0d7c8717e4f
This commit is contained in:
J. Alexander Treuman
parent
5e1deab05f
commit
fe4b16ed96
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@ -41,17 +41,17 @@
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#include <unistd.h>
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#include <errno.h>
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#define FRAMES_CUSHION 2000
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#define FRAMES_CUSHION 2000
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#define READ_BUFFER_SIZE 40960
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#define READ_BUFFER_SIZE 40960
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#define DECODE_SKIP -3
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#define DECODE_BREAK -2
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#define DECODE_CONT -1
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#define DECODE_OK 0
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#define DECODE_SKIP -3
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#define DECODE_BREAK -2
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#define DECODE_CONT -1
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#define DECODE_OK 0
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#define MUTEFRAME_SKIP 1
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#define MUTEFRAME_SEEK 2
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#define MUTEFRAME_SKIP 1
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#define MUTEFRAME_SEEK 2
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/* the number of samples of silence the decoder inserts at start */
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#define DECODERDELAY 529
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@ -498,16 +498,20 @@ enum {
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XING_SCALE = 0x00000008L
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};
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struct version {
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int major;
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int minor;
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};
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struct lame {
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char encoder[10]; /* 9 byte encoder name/version ("LAME3.97b") */
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#if 0
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/* See related comment in parse_lame() */
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float peak; /* replaygain peak */
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float trackGain; /* replaygain track gain */
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float albumGain; /* replaygain album gain */
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#endif
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int encoderDelay; /* # of added samples at start of mp3 */
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int encoderPadding; /* # of added samples at end of mp3 */
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char encoder[10]; /* 9 byte encoder name/version ("LAME3.97b") */
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struct version version; /* struct containing just the version */
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float peak; /* replaygain peak */
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float trackGain; /* replaygain track gain */
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float albumGain; /* replaygain album gain */
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int encoderDelay; /* # of added samples at start of mp3 */
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int encoderPadding; /* # of added samples at end of mp3 */
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int crc; /* CRC of the first 190 bytes of this frame */
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};
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static int parse_xing(struct xing *xing, struct mad_bitptr *ptr, int *oldbitlen)
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@ -585,52 +589,94 @@ fail:
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static int parse_lame(struct lame *lame, struct mad_bitptr *ptr, int *bitlen)
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{
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int adj = 0;
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int name;
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int orig;
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int sign;
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int gain;
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int i;
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/* Unlike the xing header, the lame tag has a fixed length. Fail if
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* not all 36 bytes (288 bits) are there. */
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if (*bitlen < 288) return 0;
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if (*bitlen < 288)
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return 0;
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for (i = 0; i < 9; i++) lame->encoder[i] = (char)mad_bit_read(ptr, 8);
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for (i = 0; i < 9; i++)
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lame->encoder[i] = (char)mad_bit_read(ptr, 8);
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lame->encoder[9] = '\0';
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*bitlen -= 72;
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/* This is technically incorrect, since the encoder might not be lame.
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* But there's no other way to determine if this is a lame tag, and we
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* wouldn't want to go reading a tag that's not there. */
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if (strncmp(lame->encoder, "LAME", 4) != 0) return 0;
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if (strncmp(lame->encoder, "LAME", 4) != 0)
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return 0;
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if (sscanf(lame->encoder+4, "%u.%u",
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&lame->version.major, &lame->version.minor) != 2)
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return 0;
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DEBUG("detected LAME version %i.%i (\"%s\")\n",
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lame->version.major, lame->version.minor, lame->encoder);
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/* The reference volume was changed from the 83dB used in the
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* ReplayGain spec to 89dB in lame 3.95.1. Bump the gain for older
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* versions, since everyone else uses 89dB instead of 83dB.
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* Unfortunately, lame didn't differentiate between 3.95 and 3.95.1, so
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* it's impossible to make the proper adjustment for 3.95.
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* Fortunately, 3.95 was only out for about a day before 3.95.1 was
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* released. -- tmz */
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if (lame->version.major < 3 ||
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(lame->version.major == 3 && lame->version.minor < 95))
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adj = 6;
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mad_bit_read(ptr, 16);
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lame->peak = mad_f_todouble(mad_bit_read(ptr, 32) << 5); /* peak */
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DEBUG("LAME peak found: %f\n", lame->peak);
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lame->trackGain = 0;
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name = mad_bit_read(ptr, 3); /* gain name */
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orig = mad_bit_read(ptr, 3); /* gain originator */
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sign = mad_bit_read(ptr, 1); /* sign bit */
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gain = mad_bit_read(ptr, 9); /* gain*10 */
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if (gain && name == 1 && orig != 0) {
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lame->trackGain = ((sign ? -gain : gain) / 10.0) + adj;
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DEBUG("LAME track gain found: %f\n", lame->trackGain);
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}
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/* tmz reports that this isn't currently written by any version of lame
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* (as of 3.97). Since we have no way of testing it, don't use it.
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* Wouldn't want to go blowing someone's ears just because we read it
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* wrong. :P -- jat */
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lame->albumGain = 0;
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#if 0
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/* Apparently lame versions <3.97b1 do not calculate replaygain. I'm
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* using lame 3.97b2, and while it does calculate replaygain, it's
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* setting the values to 0. Using --replaygain-(fast|accurate) doesn't
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* make any difference. Leaving this code unused until we have a way
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* of testing it. -- jat */
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mad_bit_read(ptr, 16);
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mad_bit_read(ptr, 32); /* peak */
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mad_bit_read(ptr, 6); /* header */
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bits = mad_bit_read(ptr, 1); /* sign bit */
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lame->trackGain = mad_bit_read(ptr, 9); /* gain*10 */
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lame->trackGain = (bits ? -lame->trackGain : lame->trackGain) / 10;
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mad_bit_read(ptr, 6); /* header */
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bits = mad_bit_read(ptr, 1); /* sign bit */
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lame->albumGain = mad_bit_read(ptr, 9); /* gain*10 */
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lame->albumGain = (bits ? -lame->albumGain : lame->albumGain) / 10;
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mad_bit_read(ptr, 16);
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name = mad_bit_read(ptr, 3); /* gain name */
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orig = mad_bit_read(ptr, 3); /* gain originator */
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sign = mad_bit_read(ptr, 1); /* sign bit */
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gain = mad_bit_read(ptr, 9); /* gain*10 */
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if (gain && name == 2 && orig != 0) {
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lame->albumGain = ((sign ? -gain : gain) / 10.0) + adj;
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DEBUG("LAME album gain found: %f\n", lame->trackGain);
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}
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#else
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mad_bit_read(ptr, 96);
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mad_bit_read(ptr, 16);
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#endif
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mad_bit_read(ptr, 16);
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lame->encoderDelay = mad_bit_read(ptr, 12);
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lame->encoderPadding = mad_bit_read(ptr, 12);
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mad_bit_read(ptr, 96);
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DEBUG("encoder delay is %i, encoder padding is %i\n",
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lame->encoderDelay, lame->encoderPadding);
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*bitlen -= 288;
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mad_bit_read(ptr, 80);
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lame->crc = mad_bit_read(ptr, 16);
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*bitlen -= 216;
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return 1;
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}
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@ -694,18 +740,30 @@ static int decodeFirstFrame(mp3DecodeData * data, DecoderControl * dc,
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data->foundXing = 1;
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data->muteFrame = MUTEFRAME_SKIP;
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if (gaplessPlaybackEnabled && data->inStream->seekable &&
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parse_lame(&lame, &ptr, &bitlen)) {
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data->dropSamplesAtStart = lame.encoderDelay + DECODERDELAY;
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data->dropSamplesAtEnd = lame.encoderPadding;
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}
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if ((xing.flags & XING_FRAMES) && xing.frames) {
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mad_timer_t duration = data->frame.header.duration;
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mad_timer_multiply(&duration, xing.frames);
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data->totalTime = ((float)mad_timer_count(duration, MAD_UNITS_MILLISECONDS)) / 1000;
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data->maxFrames = xing.frames;
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}
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if (parse_lame(&lame, &ptr, &bitlen)) {
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if (gaplessPlaybackEnabled &&
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data->inStream->seekable) {
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data->dropSamplesAtStart = lame.encoderDelay +
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DECODERDELAY;
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data->dropSamplesAtEnd = lame.encoderPadding;
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}
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/* Album gain isn't currently used. See comment in
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* parse_lame() for details. -- jat */
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if (replayGainInfo && !*replayGainInfo &&
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lame.trackGain) {
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*replayGainInfo = newReplayGainInfo();
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(*replayGainInfo)->trackGain = lame.trackGain;
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(*replayGainInfo)->trackPeak = lame.peak;
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}
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}
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}
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if (!data->maxFrames) return -1;
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