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Improve raw MP3 total samples reading

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This commit is contained in:
bnnm 2019-11-02 15:49:10 +01:00
parent 8dbdf94df4
commit 4d5ec06d76
1 changed files with 414 additions and 372 deletions
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106
src/coding/mpeg_custom_utils.c
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@ -234,7 +234,7 @@ fail:
* Gets info from a MPEG frame header at offset. Normally you would use mpg123_info but somehow
* it's wrong at times (maybe because we use an ancient version) so here we do our thing.
*/
int mpeg_get_frame_info(STREAMFILE *streamfile, off_t offset, mpeg_frame_info * info) {
static int mpeg_get_frame_info_h(uint32_t header, mpeg_frame_info *info) {
/* index tables */
static const int versions[4] = { /* MPEG 2.5 */ 3, /* reserved */ -1, /* MPEG 2 */ 2, /* MPEG 1 */ 1 };
static const int layers[4] = { -1,3,2,1 };
@ -257,14 +257,11 @@ int mpeg_get_frame_info(STREAMFILE *streamfile, off_t offset, mpeg_frame_info *
{ 384, 1152, 576 } /* MPEG2.5 */
};
uint32_t header;
int idx, padding;
memset(info, 0, sizeof(*info));
header = read_32bitBE(offset, streamfile);
if ((header >> 21) != 0x7FF) /* 31-21: sync */
goto fail;
@ -308,34 +305,36 @@ int mpeg_get_frame_info(STREAMFILE *streamfile, off_t offset, mpeg_frame_info *
fail:
return 0;
}
int mpeg_get_frame_info(STREAMFILE *sf, off_t offset, mpeg_frame_info *info) {
uint32_t header = read_u32be(offset, sf);
return mpeg_get_frame_info_h(header, info);
}
size_t mpeg_get_samples(STREAMFILE *streamFile, off_t start_offset, size_t bytes) {
size_t mpeg_get_samples(STREAMFILE *sf, off_t start_offset, size_t bytes) {
off_t offset = start_offset;
off_t max_offset = start_offset + bytes;
int samples = 0;
int frames = 0, samples = 0, encoder_delay = 0, encoder_padding = 0;
mpeg_frame_info info;
size_t prev_size = 0;
int cbr_count = 0;
int is_vbr = 0;
if (!streamFile)
if (!sf)
return 0;
if (max_offset > get_streamfile_size(streamFile))
max_offset = get_streamfile_size(streamFile);
if (max_offset > get_streamfile_size(sf))
max_offset = get_streamfile_size(sf);
/* MPEG may use VBR so must read all frames */
while (offset < max_offset) {
uint32_t header = read_u32be(offset+0x00, sf);
/* skip ID3v2 */
if ((read_32bitBE(offset+0x00, streamFile) & 0xFFFFFF00) == 0x49443300) { /* "ID3\0" */
if ((header & 0xFFFFFF00) == 0x49443300) { /* "ID3\0" */
size_t frame_size = 0;
uint8_t flags = read_8bit(offset+0x05, streamFile);
uint8_t flags = read_u8(offset+0x05, sf);
/* this is how it's officially read :/ */
frame_size += read_8bit(offset+0x06, streamFile) << 21;
frame_size += read_8bit(offset+0x07, streamFile) << 14;
frame_size += read_8bit(offset+0x08, streamFile) << 7;
frame_size += read_8bit(offset+0x09, streamFile) << 0;
frame_size += read_u8(offset+0x06, sf) << 21;
frame_size += read_u8(offset+0x07, sf) << 14;
frame_size += read_u8(offset+0x08, sf) << 7;
frame_size += read_u8(offset+0x09, sf) << 0;
frame_size += 0x0a;
if (flags & 0x10) /* footer? */
frame_size += 0x0a;
@ -344,28 +343,71 @@ size_t mpeg_get_samples(STREAMFILE *streamFile, off_t start_offset, size_t bytes
continue;
}
/* this may fail with unknown ID3 tags */
if (!mpeg_get_frame_info(streamFile, offset, &info))
break;
if (prev_size && prev_size != info.frame_size) {
is_vbr = 1;
}
else if (!is_vbr) {
cbr_count++;
/* skip ID3v1 */
if ((header & 0xFFFFFF00) == 0x54414700) { /* "TAG\0" */
;VGM_LOG("MPEG: ID3v1 at %lx\n", offset);
offset += 0x80;
continue;
}
if (cbr_count >= 10) {
/* must be CBR, don't bother counting */
samples = (bytes / info.frame_size) * info.frame_samples;
/* regular frame */
if (!mpeg_get_frame_info_h(header, &info)) {
VGM_LOG("MPEG: unknown frame at %lx\n", offset);
break;
}
/* detect Xing header (disguised as a normal frame) */
if (frames < 3 && /* should be first after tags */
info.frame_size >= 0x24 + 0x78 &&
read_u32be(offset + 0x04, sf) == 0 &&
(read_u32be(offset + 0x24, sf) == 0x58696E67 || /* "Xing" (mainly for VBR) */
read_u32be(offset + 0x24, sf) == 0x496E666F)) { /* "Info" (mainly for CBR) */
uint32_t flags = read_u32be(offset + 0x28, sf);
if (flags & 1) { /* other flags indicate seek table and stuff */
uint32_t frame_count = read_u32be(offset + 0x2c, sf);
samples = frame_count * info.frame_samples;
}
/* vendor specific */
if (info.frame_size > 0x24 + 0x78 + 0x24 &&
read_u32be(offset + 0x9c, sf) == 0x4C414D45) { /* "LAME" */
if (info.layer == 3) {
uint32_t delays = read_u32be(offset + 0xb0, sf);
encoder_delay = ((delays >> 12) & 0xFFF);
encoder_padding = ((delays >> 0) & 0xFFF);
encoder_delay += (528 + 1); /* implicit MDCT decoder delay (seen in LAME source) */
if (encoder_padding > 528 + 1)
encoder_padding -= (528 + 1);
}
else {
encoder_delay = 240 + 1;
}
/* replay gain and stuff */
}
/* there is also "iTunes" vendor with no apparent extra info, iTunes delays are in "iTunSMPB" ID3 tag */
;VGM_LOG("MPEG: found Xing header\n");
break; /* we got samples */
}
//TODO: detect "VBRI" header (Fraunhofer encoder)
// https://www.codeproject.com/Articles/8295/MPEG-Audio-Frame-Header#VBRIHeader
/* could detect VBR/CBR but read frames to remove ID3 end tags */
frames++;
offset += info.frame_size;
prev_size = info.frame_size;
samples += info.frame_samples; /* header frames may be 0? */
samples += info.frame_samples;
}
;VGM_LOG("MPEG: samples=%i, ed=%i, ep=%i, end=%i\n", samples,encoder_delay,encoder_padding, samples - encoder_delay - encoder_padding);
//todo return encoder delay
samples = samples - encoder_delay - encoder_padding;
return samples;
}