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ps2_gcm comment tweaks

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modusc896d352 2022-07-01 22:49:47 -03:00 committed by GitHub
parent 19b714bc6e
commit 7eea28ae0e
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1 changed files with 20 additions and 20 deletions
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40
src/meta/ps2_gcm.c
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@ -19,7 +19,7 @@ VGMSTREAM* init_vgmstream_ps2_gcm(STREAMFILE* sf) {
goto fail;
/* GCM format as Namco outlined it is a hacked VAGp stereo format that can hold 6-channel audio at will.
* so, first step is to let's deal with whatever quirks the format might have */
* so, first step is to deal with whatever quirks the format might have. */
vagp_l_offset = read_u32le(0x04, sf); /* "left" VAGp header pointer. */
if (vagp_l_offset != 0x20)
goto fail;
@ -29,10 +29,10 @@ VGMSTREAM* init_vgmstream_ps2_gcm(STREAMFILE* sf) {
start_offset = read_u32le(0x0c, sf); /* raw "stereo VAG" data pointer. */
if (start_offset != 0x80)
goto fail;
gcm_samples = read_u32le(0x10, sf); /* size of raw "stereo VAG" data, not correct for multi - channel files as we'll see below. */
gcm_samples = read_u32le(0x10, sf); /* size of raw "stereo VAG" data, not exactly correct for multi-channel files as we'll see below. */
/* second step is to check actual GCM size and decide channels value from there.
* not helping matters is there's nothing in the GCM header that indicates that this file is multi-channel or not.
/* second step is to check actual GCM size and decide the "channels" value from there.
* not helping matters is there's nothing in the GCM header that indicates whether or not this GCM is actually multi-channel in any way.
* meaning we have to manually support those Klonoa multi-channel files (KLN3182M.GCM, KLN3191M.GCM, etc). */
data_size = get_streamfile_size(sf) - start_offset;
if (data_size == (gcm_samples * 3)) {
@ -47,56 +47,56 @@ VGMSTREAM* init_vgmstream_ps2_gcm(STREAMFILE* sf) {
/* there is only one known GCM "multi-channel" setup and it's hacky. */
goto fail;
}
/* what follows are two VAGp headers and raw data, check VAGp header values and see if they match */
/* what follows are two VAGp headers and raw data, third and final step is to perform sanity checks on them (except the data itself) and go from there. */
/* VAGp signature field, always present */
/* VAGp signature field, always present. */
uint32_t vagp_l_sig, vagp_r_sig, vagp_sig;
vagp_l_sig = read_u32be(vagp_l_offset, sf);
vagp_r_sig = read_u32be(vagp_r_offset, sf);
if (vagp_l_sig != vagp_r_sig) {
/* check two identical values against each other */
/* check two identical values against each other. */
goto fail;
}
else {
/* check for "VAGp" value */
/* check for "VAGp" value. */
vagp_sig = vagp_r_sig;
if (vagp_sig != 0x56414770) goto fail; /* "VAGp" */
}
/* VAGp version field, always 4 */
/* VAGp version field, always 4. */
uint32_t vagp_l_ver, vagp_r_ver, vagp_ver;
vagp_l_ver = read_u32be(vagp_l_offset + 4, sf);
vagp_r_ver = read_u32be(vagp_r_offset + 4, sf);
if (vagp_l_ver != vagp_r_ver) {
/* check two identical values against each other */
/* check two identical values against each other. */
goto fail;
}
else {
/* check for "version 4" value */
/* check for "version 4" value. */
vagp_ver = vagp_r_ver;
if (vagp_ver != 4) goto fail;
}
/* VAGp size field, usually separate per channel and does not cover blank frames at all */
/* VAGp size field, usually separate per channel and does not cover blank frames at all. */
uint32_t vagp_l_size, vagp_r_size, vagp_samples;
vagp_l_size = read_u32be(vagp_l_offset + 12, sf);
vagp_r_size = read_u32be(vagp_r_offset + 12, sf);
if (vagp_l_size != vagp_r_size) {
/* check two identical values against each other */
/* check two identical values against each other. */
goto fail;
}
else {
/* assign one of the two existing "vag size" values to an entirely new "vag size" variable to be used later */
/* assign one of the two existing "vag size" values to an entirely new "vag size" variable to be used later. */
vagp_samples = vagp_r_size;
}
/* VAGp sample rate field, usually separate per channel */
/* VAGp sample rate field, usually separate per channel. */
uint32_t vagp_l_sample_rate, vagp_r_sample_rate;
vagp_l_sample_rate = read_u32be(vagp_l_offset + 16, sf);
vagp_r_sample_rate = read_u32be(vagp_r_offset + 16, sf);
if (vagp_l_sample_rate != vagp_r_sample_rate) {
/* check two identical values against each other */
/* check two identical values against each other. */
goto fail;
}
else {
/* assign one of the two existing sample rate values to an entirely new sample rate variable to be used later */
/* assign one of the two existing "sample rate" values to an entirely new "sample rate" variable to be used later. */
gcm_sample_rate = vagp_r_sample_rate;
}
@ -105,7 +105,7 @@ VGMSTREAM* init_vgmstream_ps2_gcm(STREAMFILE* sf) {
vgmstream = allocate_vgmstream(gcm_channels,0);
if (!vgmstream) goto fail;
/* fill in the vital statistics */
/* fill in the vital statistics. */
vgmstream->meta_type = meta_PS2_GCM;
vgmstream->sample_rate = gcm_sample_rate;
vgmstream->num_samples = ps_bytes_to_samples(vagp_samples, 1);
@ -113,12 +113,12 @@ VGMSTREAM* init_vgmstream_ps2_gcm(STREAMFILE* sf) {
vgmstream->layout_type = layout_interleave;
vgmstream->interleave_block_size = read_u32le(0x14, sf);
/* open the file for reading */
/* open the file for reading. */
if (!vgmstream_open_stream(vgmstream, sf, start_offset))
goto fail;
return vgmstream;
/* clean up anything we may have opened */
/* clean up anything we may have opened. */
fail:
close_vgmstream(vgmstream);
return NULL;