If you are using Mega PCM 1.x, you still can easily replace it with Mega PCM 2 and enjoy higher sample rates, volume control, ultra-clean playback on real hardware and other neat features!
- Migration overview
- Step 1. Following the installation guide
- Step 2. Converting the sample table
- Step 3. Converting sample rates and samples
Mega PCM 2.x was designed with backwards compatibility in mind and supports the same sample formats and flags as Mega PCM 1.x. But since 2.x is a complete rewrite, there are notable changes in how certain features are implemented.
However, if you have a stock installation of Mega PCM 1.x (not something heavily-modified like Mega PCM 1.x on Sonic 2 Clone Driver), the migration should be pretty straight-forward and you only need to worry about 3 things:
-
Following Mega PCM 2 installation guide and making sure your final code changes match what the guide expects after a clean installation.
-
Converting your sample table to Mega PCM 2 format.
-
If you're unlucky to have DPCM and PCM samples with a very specific pitches in 1.x, you need to convert them to PCM/WAV and/or upsample/downsample to the nearest supported sample rate. But 95% of samples should work without conversion.
Now let's go over those 3 migration steps one-by-one!
Note
If you want to just port your sample table from Mega PCM 1.x to a clean Mega PCM 2 source, skip this step and go right to the next one.
Follow the right installation guide for your disassembly, but bear in mind important notes below:
Important notes:
-
Since you installed Mega PCM 1.x before, you may find out that some of the steps are already complete or done in a different way. On each step make sure that your code matches what the guide expects after a clean installation.
-
If you previously followed "HQ playback guide" for 1.x, "Step 2. Remove Z80 stops globally" should already be completed. But double-check everything, because failing this step will result in broken Mega PCM 2 installation!
-
When it's time to insert a sample table you may realize you're not ready to convert your old one yet. Don't worry, just go with the one guide provides you with. Nothing will break, Mega PCM just won't play non-existing samples.
Converting sample table format from version 1.x to 2.x should be pretty straight-forward if you precisely follow the instructions below. Mega PCM 2 implements error handling in many places, making it hard to break.
First let's compare and break down a simple sample table:
Mega PCM 1.x format:
; pitch, pointer, type+flags
DAC_Entry $08, Kick, dpcm ; $81
DAC_Entry $08, Snare, dpcm ; $82
DAC_Entry $1B, Timpani, dpcm ; $83
DAC_Entry $02, MySFX, pcm+pri ; $84
MegaPCM_End:
; ---------------------------------------------------------------
IncludeDAC Kick, dpcm
IncludeDAC Snare, dpcm
IncludeDAC Timpani, dpcm
IncludeDAC MySFX, wavMega PCM 2.x format:
SampleTable:
; type pointer Hz (0 = auto-detect)
dcSample TYPE_DPCM, Kick, 8000 ; $81
dcSample TYPE_PCM, Snare, 24000 ; $82
dcSample TYPE_DPCM, Timpani, 7250 ; $83
dcSample TYPE_PCM, MySFX, 0, FLAGS_SFX ; $84
dc.w -1 ; end marker
; ---------------------------------------------------------------
incdac Kick, "sound/dac/Kick.dpcm"
incdac Snare, "sound/dac/Snare.pcm"
incdac Timpani, "sound/dac/Timpani.dpcm"
incdac MySFX, "sound/dac/MySFX.wav"Version 2.x uses a different set of macros (DAC_Entry -> dcSample, IncludeDAC -> incdac), so let's go over converting their invocations in detail.
General formula is the following:
IncludeDAC <Name>, <ext> To:
incdac <Name>, "sound/dac/<Name>.<ext>"Mega PCM 1.x auto-generated sound/dac/<Name>.<ext> path under the hood, while Mega PCM 2 is being more explicit and flexible: you're no longer locked to sound/dac directory and your sample's filename and its label/pointer can differ!
Given the example above, here's what you should get before and after conversion:
Before the conversion (Mega PCM 1.x format):
IncludeDAC Kick, dpcm
IncludeDAC Snare, dpcm
IncludeDAC Timpani, dpcm
IncludeDAC MySFX, wavAfter the conversion (Mega PCM 2.x format):
incdac Kick, "sound/dac/Kick.dpcm"
incdac Snare, "sound/dac/Snare.dpcm"
incdac Timpani, "sound/dac/Timpani.dpcm"
incdac MySFX, "sound/dac/MySFX.wav"Note
Some heavily modified projects may customize paths, so it can differ from the default sound/dac/<Name>.<ext>. Just in case, you may find the definition of IncludeDAC macro to verify it, or just see where DAC samples are stored in your disassembly.
This conversion is a bit more involved as this is where the formats differ the most.
General formula is the following:
DAC_Entry <1.x_Pitch>, <Name>, <1.x_Type_and_Flags>To:
dcSample <2.x_Type>, <Name>[, <2.x_SampleRate>, <2.x_Flags>]Instead of going into the detail of converting every field of every line, we can easily automate it using your editor's search&replace and copy&paste capabilities! Here's a step by step conversion routine:
-
We start with the stock 1.x format, where only the
<Name>column accidentally matches Mega PCM 2's format (✅), everything else is incompatible (❌):; ❌ ❌ ✅ ❌ DAC_Entry $08, Kick, dpcm ; $81 DAC_Entry $08, Snare, dpcm ; $82 DAC_Entry $1B, Timpani, dpcm ; $83 DAC_Entry $02, MySFX, pcm+pri ; $84
-
Now, let's replace
DAC_EntrywithdcSample, swap the first and the third columns and adddc.w -1(end marker) after the last sample as shown below:; ✅ ❌ ✅ ❌ dcSample dpcm, Kick, $08 ; $81 dcSample dpcm, Snare, $08 ; $82 dcSample dpcm, Timpani, $1B ; $83 dcSample pcm+pri, MySFX, $02 ; $84 dc.w -1 ; ++ end marker
Macro name is now compatible (✅), other columns are taking their correct places, but still use wrong formats (❌).
Warning
Always remember to add end marker (dc.w -1) to your sample table. Otherwise, you may see failures upon boot!
-
Do the following replacements inside the table only (not globally!):
pcm=>TYPE_PCMdpcm=>TYPE_DPCMpri=>FLAGS_SFX(if exists)loop=>FLAGS_LOOP(if exists)panLR,panLandpanR=> nothing (remove them, Mega PCM 2 handles panning differently);
You should get the following:
; ✅ ⚠️ ✅ ❌ dcSample TYPE_DPCM, Kick, $08 ; $81 dcSample TYPE_DPCM, Snare, $08 ; $82 dcSample TYPE_DPCM, Timpani, $1B ; $83 dcSample TYPE_PCM+FLAGS_SFX, MySFX, $02 ; $84 dc.w -1
The first column (
<2.x_Type>) is now almost compatible, but some instances with flags need correction (⚠️ ), see below. -
If some records in the first column (
<2.x_Type>) have leftover flags after previous manipulations (e.g.TYPE_PCM+FLAGS_SFX), you need to move everything after the first+character to a new dedicated column (<2.x_Flags>):; ✅ ✅ ✅ ❌ ✅ dcSample TYPE_DPCM, Kick, $08 ; $81 dcSample TYPE_DPCM, Snare, $08 ; $82 dcSample TYPE_DPCM, Timpani, $1B ; $83 dcSample TYPE_PCM, MySFX, $02, FLAGS_SFX ; $84 dc.w -1
Now, almost everything is properly converted, except for the
<2.x_SampleRate>column (❌), which still uses values of<1.x_Pitch>. This final conversion is the most nuanced one, hence deserves its own topic, so let's go right into the next chapter below.
Note
If you have hard times following column/field names (e.g. <2.x_Flags>) and why everything was being swapped and replaced in the steps above, revisit the general conversion formula above and compare 1.x and 2.x syntax.
In the previous step, we almost fully converted the sample table from 1.x to 2.x format, except for one part: pitches.
With Mega PCM 2 you can specify proper sample rates in Hz, while 1.x used an arbitrary pitch bytes specific to driver's internal timing which you had to fine-tune manually. Each "pitch" value from 1.x has a corresponding effective sample rate, except it's not explicitly specified like with 2.x and it differs between PCM and DPCM playback code.
For example, the pitch value of $08 for DPCM sample will maintain playback at ~17478 Hz. For your convenience, there are tables for converting "pitches" to actual sample rates below, but first let's discuss supported sample rate differences between Mega PCM 1.x and 2.0.
Unfortunately, some pitches from 1.x are incompatible, especially for DPCM. This means that a few DPCM samples have to be converted to PCM format (most notably, S1/S2/S3K Snare) and, in rare cases, some PCM samples need to be upsampled or downsampled to the nearest supported rate.
Summary of supported rates:
| Mega PCM 1.x | Mega PCM 2.0 | |
|---|---|---|
| PCM/WAV | 1050 .. 28500 Hz | 0 .. 25100 Hz (normal mode) 32000 Hz fixed (turbo mode) |
| DPCM | 1050 .. 31450 Hz | 0 .. 20500 Hz |
As you can see, Mega PCM 2 has a higher maximum playback rate in turbo mode. However, due to addition of volume and pitch control in normal modes, max PCM rate is slightly lower and max DPCM rate is noticeably lower because Mega PCM 2's streaming system wasn't designed for DPCM (it was mostly added for feature-parity).
General takeaways from the above table:
- If your DPCM sample's rate is higher than 20500 Hz, you need to convert it to PCM;
- If your PCM sample's rate is between 25100 and 28500 Hz, you need to either downsample it to 25100 Hz (recommended) or upsample to 32000 Hz.
- In every other case, you can set the correct sample rate without sample data conversion.
Most of the times, you won't need any conversion at all. If you do, it's quite simple using proper tools, which we'll discuss soon. But first, let's finally convert pitches to sample rates!
Let's take another look at our "mostly converted" sample table from the previous step:
; ✅ ✅ ✅ ❌ ✅
dcSample TYPE_DPCM, Kick, $08 ; $81
dcSample TYPE_DPCM, Snare, $08 ; $82
dcSample TYPE_DPCM, Timpani, $1B ; $83
dcSample TYPE_PCM, MySFX, $02, FLAGS_SFX ; $84
dc.w -1We need to go over raw values in the third column (marked with ❌, because it requires conversion).
Just take raw "pitch" value from this table (e.g. $08, $1B, $02 etc) and replace it with "sample rate" value using the tables below.
Pay attention to sample type! Use different tables for TYPE_PCM and TYPE_DPCM. Table may instruct to to convert sample due to limitations listed in the previous subsection. Converting samples themselves (only if you need this) will be covered in the next section.
If you complete follow next sections carefully, you should get the following result (use it as a reference to check yourself later if needed):
; ✅ ✅ ✅ ✅ ✅
dcSample TYPE_DPCM, Kick, 17478 ; $81
dcSample TYPE_DPCM, Snare, 17478 ; $82
dcSample TYPE_DPCM, Timpani, 8000 ; $83 (rounded)
dcSample TYPE_PCM, MySFX, 25100, FLAGS_SFX ; $84 (rounded)
dc.w -1Note
For more information on Mega PCM 2's sample table format, see Mega PCM 2 Sample table format.
Use this table if your target sample's type is TYPE_PCM. Note that allowed pitches in 1.x are $01..$FF, but only $01..$3F are covered here, because anything above is so low, it's not practically usable.
| Mega PCM 1.x Pitch | Converted Mega PCM 2.x Sample rate, Hz |
|---|---|
| $01 (1) | 28568 |
| $02 (2) | 25882 (UNSUPPORTED, round to 25100 Hz) |
| $03 (3) | 23659 |
| $04 (4) | 21787 (can be rounded to 22050 Hz if that was the original rate) |
| $05 (5) | 20189 |
| $06 (6) | 18810 |
| $07 (7) | 17607 |
| $08 (8) | 16549 (can be rounded to 16000 Hz if that was the original rate) |
| $09 (9) | 15611 (can be rounded to 16000 Hz if that was the original rate) |
| $0A (10) | 14773 |
| $0B (11) | 14021 |
| $0C (12) | 13342 |
| $0D (13) | 12725 |
| $0E (14) | 12163 |
| $0F (15) | 11648 |
| $10 (16) | 11176 (can be rounded to 11000 Hz if that was the original rate) |
| $11 (17) | 10740 (can be rounded to 11000 Hz if that was the original rate) |
| $12 (18) | 10337 |
| $13 (19) | 9963 |
| $14 (20) | 9615 |
| $15 (21) | 9290 |
| $16 (22) | 8987 |
| $17 (23) | 8703 |
| $18 (24) | 8436 |
| $19 (25) | 8186 (can be rounded to 8000 Hz if that was the original rate) |
| $1A (26) | 7949 (can be rounded to 8000 Hz if that was the original rate) |
| $1B (27) | 7726 |
| $1C (28) | 7515 |
| $1D (29) | 7316 |
| $1E (30) | 7126 |
| $1F (31) | 6947 |
| $20 (32) | 6776 |
| $21 (33) | 6613 |
| $22 (34) | 6458 |
| $23 (35) | 6310 |
| $24 (36) | 6168 |
| $25 (37) | 6033 |
| $26 (38) | 5904 |
| $27 (39) | 5780 |
| $28 (40) | 5661 |
| $29 (41) | 5547 |
| $2A (42) | 5438 |
| $2B (43) | 5332 |
| $2C (44) | 5231 |
| $2D (45) | 5133 |
| $2E (46) | 5039 |
| $2F (47) | 4949 |
| $30 (48) | 4862 |
| $31 (49) | 4777 |
| $32 (50) | 4696 |
| $33 (51) | 4617 |
| $34 (52) | 4541 |
| $35 (53) | 4467 |
| $36 (54) | 4396 |
| $37 (55) | 4327 |
| $38 (56) | 4260 |
| $39 (57) | 4195 |
| $3A (58) | 4132 |
| $3B (59) | 4071 |
| $3C (60) | 4012 (can be rounded to 4000 Hz if that was the original rate) |
| $3D (61) | 3954 (can be rounded to 4000 Hz if that was the original rate) |
| $3E (62) | 3898 |
| $3F (63) | 3844 |
Use this table if your target sample's type is TYPE_DPCM. Note that allowed pitches in 1.x are $01..$FF, but only $01..$3F are covered here, because anything above is so low, it's not practically usable.
| Mega PCM 1.x Pitch | Converted Mega PCM 2.x Sample rate, Hz |
|---|---|
| $01 (1) | 31455 (UNSUPPORTED! Convert to TYPE_PCM_TURBO at ~32000 Hz) |
| $02 (2) | 28230 (UNSUPPORTED! Convert to TYPE_PCM_TURBO at ~32000 Hz) |
| $03 (3) | 25605 (UNSUPPORTED! Convert to TYPE_PCM at ~25100 Hz) |
| $04 (4) | 23426 (UNSUPPORTED! Convert to TYPE_PCM at 23426 Hz) |
| $05 (5) | 21590 (UNSUPPORTED! Convert to TYPE_PCM at 21590 Hz or 22050 Hz if rounded) |
| $06 (6) | 20020 |
| $07 (7) | 18663 |
| $08 (8) | 17478 |
| $09 (9) | 16435 (can be rounded to 16000 Hz if that was the original rate) |
| $0A (10) | 15509 (can be rounded to 16000 Hz if that was the original rate) |
| $0B (11) | 14682 |
| $0C (12) | 13939 |
| $0D (13) | 13267 |
| $0E (14) | 12658 |
| $0F (15) | 12101 |
| $10 (16) | 11592 |
| $11 (17) | 11124 (can be rounded to 11025 Hz if that was the original rate) |
| $12 (18) | 10692 (can be rounded to 11025 Hz if that was the original rate) |
| $13 (19) | 10292 |
| $14 (20) | 9921 |
| $15 (21) | 9576 |
| $16 (22) | 9254 |
| $17 (23) | 8953 |
| $18 (24) | 8671 |
| $19 (25) | 8407 |
| $1A (26) | 8158 (can be rounded to 8000 Hz if that was the original rate) |
| $1B (27) | 7923 (can be rounded to 8000 Hz if that was the original rate) |
| $1C (28) | 7701 |
| $1D (29) | 7492 |
| $1E (30) | 7293 |
| $1F (31) | 7105 |
| $20 (32) | 6926 |
| $21 (33) | 6756 |
| $22 (34) | 6595 |
| $23 (35) | 6440 |
| $24 (36) | 6293 |
| $25 (37) | 6153 |
| $26 (38) | 6018 |
| $27 (39) | 5889 |
| $28 (40) | 5766 |
| $29 (41) | 5648 |
| $2A (42) | 5534 |
| $2B (43) | 5425 |
| $2C (44) | 5320 |
| $2D (45) | 5220 |
| $2E (46) | 5122 |
| $2F (47) | 5029 |
| $30 (48) | 4939 |
| $31 (49) | 4852 |
| $32 (50) | 4768 |
| $33 (51) | 4686 |
| $34 (52) | 4608 |
| $35 (53) | 4532 |
| $36 (54) | 4459 |
| $37 (55) | 4388 |
| $38 (56) | 4319 |
| $39 (57) | 4252 |
| $3A (58) | 4188 |
| $3B (59) | 4125 |
| $3C (60) | 4064 (can be rounded to 4000 Hz if that was the original rate) |
| $3D (61) | 4005 (can be rounded to 4000 Hz if that was the original rate) |
| $3E (62) | 3947 (can be rounded to 4000 Hz if that was the original rate) |
| $3F (63) | 3892 |
Only follow these steps if tables above instruct you to convert samples themselves. You won't need this for 95% of samples.
If you have DPCM samples and the table above instructed you to convert some of them to PCM, just follow the instructions below:
- You need to get
dpcm2pcm.exeutility, which you can download here: https://vladikcomper.scanf.su/public/dpcm2pcm.7z (it's also available in SMPS Research Pack, Linux/MacOS may build it from the source code) - Extract
dpcm2pcm.exeto yoursound/dacdirectory for convenience. - Drag and drop a DPCM sample (e.g.
snare.dpcm) to convert onto thedpcm2pcm.exe, you should see a new file with.sndextension next to it (e.g.snare.dpcm.snd) - Use that new sample instead of an old one. Don't forget to change
TYPE_DPCMtoTYPE_PCMin the table!
As mentioned before, if your PCM sample's rate was between 25100 and 28500 Hz, you need to either downsample it to 25100 Hz (recommended) or upsample to 32000 Hz, because any rate in-between isn't supported by Mega PCM 2.
If your old rate was close enough to the supported boundary (e.g. 25800 instead of 25100 Hz), you can just "round" it and call it a day; a difference won't be audible anyways.
In other cases, you need to decide between downsampling to 25100 Hz or upsampling to 32000 Hz (or if you still have a higher quality source, converting it again targeting the supported rate). Downsampling is preferred in most of the cases, because 32000 Hz playback mode doesn't support volume control and sample size will be larger.
The following instruction uses Audacity to perform conversion:
- Open your sample in Audacity:
- If it's a WAV file, it will be opened automatically;
- If it's a RAW PCM data, you need to import it via File > Import > Raw data (set type to 8-bit unsigned PCM, Mono, set the original Sample rate you need to convert from)
- In the bottom section of the screen, find "Project rate (Hz)" field and set it:
- To 25100 Hz to downsample (recommended);
- To 32000 Hz to upsample;
- Export sample as WAV file via File > Export > Export as WAV. Make sure to select "WAV (Microsoft)" type and "Unsigned 8-bit PCM" encoding.
- Use your newly saved .WAV file in Mega PCM 2 with the following settings:
- Set type to
TYPE_PCMif it was downsampled; - Set type to
TYPE_PCM_TURBOit was upsampled to 32000 Hz; - In both cases, you can set Sample rate in the table to 0, so Mega PCM 2 will detect it automatically.
- Set type to