Flipnote Files/PPM: Difference between revisions

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Line 383:

| 4

| Size of the background music.

| The size of the background music in bytes in the audio data below~~, max size is 0x2000~~. 0x0 if not used/empty.

| The size of the background music in bytes in the audio data below. 0x0 if not used/empty.

|-

| 4

Line 398:

|-

| 1

| ~~Given~~ Framespeed.

| Current Framespeed.

| This is the speed of the flipnote. It's in the range of 1-8. To get the correct value, you must take 8, and subtract the decimal value of this byte.

|-

| 1

| ~~Current~~ Framespeed when BGM was recorded.

| Given Framespeed when BGM was recorded.

| This is the speed of the flipnote when the BGM was recorded/modified. It's in the range of 1-8. This is used to resample the sound to the new speed. To get the correct value, you must take 8, and subtract the decimal value of this byte.

|-

Line 420:

*Then comes sound effect #3(if used)

The sound data appears to be PCM, 1 channel, 8 bits per sample, at 4096 Hz. When played back with these parameters, the audio is quite audible, BUT there is a lot of background hiss. Perhaps there is a low pass filter on the DSi audio output?

~~----~~

The sound data is 4bit ADPCM with reversed nibbles @ 8kHz.

~~I have yet to figure out how to get rid of~~ the ~~noice when decoding~~ sound~~...~~--[[~~User:Pbsds|pbsds]~~] ~~17:38, 6 June 2010 (UTC)~~

You can decode the sound yourself with "sox -t ima -N [input] [output]"

==Signature==

The last 0x10-bytes in a PPM are all-zero. The 0x80 bytes before that is a RSA-1024 SHA-1 signature over the whole PPM, excluding the last 0x90 bytes with the signature.

@@ Line 383: / Line 383: @@
 | 4
 | Size of the background music.
-| The size of the background music in bytes in the audio data below, max size is 0x2000. 0x0 if not used/empty.
+| The size of the background music in bytes in the audio data below. 0x0 if not used/empty.
 |-
 | 4
@@ Line 398: / Line 398: @@
 |-
 | 1
-| Given Framespeed.
+| Current Framespeed.
 | This is the speed of the flipnote. It's in the range of 1-8. To get the correct value, you must take 8, and subtract the decimal value of this byte.
 |-
 | 1
-| Current Framespeed when BGM was recorded.
+| Given Framespeed when BGM was recorded.
 | This is the speed of the flipnote when the BGM was recorded/modified. It's in the range of 1-8. This is used to resample the sound to the new speed. To get the correct value, you must take 8, and subtract the decimal value of this byte.
 |-
@@ Line 420: / Line 420: @@
 *Then comes sound effect #3(if used)
-The sound data appears to be PCM, 1 channel, 8 bits per sample, at 4096 Hz. When played back with these parameters, the audio is quite audible, BUT there is a lot of background hiss. Perhaps there is a low pass filter on the DSi audio output?
-----
+The sound data is 4bit ADPCM with reversed nibbles @ 8kHz.
-I have yet to figure out how to get rid of the noice when decoding sound...--[[User:Pbsds|pbsds]] 17:38, 6 June 2010 (UTC)
+You can decode the sound yourself with "sox -t ima -N [input] [output]"
 ==Signature==
 The last 0x10-bytes in a PPM are all-zero. The 0x80 bytes before that is a RSA-1024 SHA-1 signature over the whole PPM, excluding the last 0x90 bytes with the signature.