Changes between Version 23 and Version 24 of SV8Specification

Timestamp:

11/23/06 18:18:38 (18 years ago)

Author:

r2d

Comment:

--

SV8Specification

@@ -37 +37 @@
 || '''Block name''' || '''Key''' || '''Mandatory''' ||
 || Stream information || SI || yes ||
-|| Replay gain || RG || yes ||
 || Encoder information || EI || no ||
 || Audio data || AD || yes ||
@@ -51 +50 @@
 || '''Field''' || '''length (bits)''' || '''Value''' || '''comment''' ||
 || CRC || 32 ||  || CRC 32 of the block (this field excluded). 0 = invalid ||
-|| Version || 8 || 0x08 || bitstream version ||
+|| Info length || n*8; 0 < n < 10 ||  || length (in bytes) from this field (included) to the ReplayGain version field ||
+|| Stream version || 8 || 0x08 || bitstream version ||
 || Sample count || n*8; 0 < n < 10 ||  || number of samples in the stream. 0 = unknow ||
-|| Sample Frequency || 4 ||  || see table below ||
+|| Sample frequency || 4 ||  || see table below ||
 || Channel count || 4 || 1..16 || number of channels in the stream ||
 || Max used bands || 5 || 1..32 || maximum number of bands used in the file ||
-|| ~~IS used~~ || ~~1~~ ||  || IntensityStereo. Klemm specification suggest to use the number of band always using IS ? From the source, this flag is always set to 0 and marked as not supported anymore. Even the decoder doesn't read it and set it to 0. This flag will be removed ||
 || MS used || 1 ||  || MidSideStereo ||
-|| ~~PNS used~~ || ~~1~~ ||  || The decoder doesn't use this information -> move it to EI block ? ||
 || Audio block frames || 4 || 0..15 || number of frames in an audio block is : 2^Value^ (1..32768) ||
 || Unused || 6 ||  || must be 0 ||
+|| ReplayGain version || 8 ||  || The replay gain version - must be aligned on a byte - ||
+|| Title gain || 16 ||  || The loudness calculated for the title, ''and not the gain that the player must apply'' ||
+|| Title peak || 16 ||  ||  ||
+|| Album gain || 16 ||  || The loudness calculated for the album ||
+|| Album peak || 16 ||  ||  ||
 
 Do we need to specify the channel position ? Is there standard positions / order of the channels ?
@@ -72 +75 @@
 || 4 || 96000 ||
 
-The CRC used in this block needs to be define.
+The CRC used is this one : [http://www.w3.org/TR/PNG/#D-CRCAppendix http://www.w3.org/TR/PNG/#D-CRCAppendix].
 
-
-== Replay gain block ==
-
-This block key is "RG".[[BR]]
-This block contains replay gain datas. This block is mandatory and must be written before the first audio block.[[BR]]
-Values stored in dB in Q8.8 format (maybe Q7.9 or relative to the max value for the bitdepth is better ?).[[BR]]
-
-|| '''Field''' || '''length (bits)''' || '''Value''' || '''comment''' ||
-|| Version || 8 ||  || The replay gain version ||
-|| Title gain || 16 ||  || The loudness calculated for the title, ''and not the gain that the player must apply'' ||
-|| Title peak || 16 ||  ||  ||
-|| Album gain || 16 ||  || The loudness calculated for the album ||
-|| Album peak || 16 ||  ||  ||
+The replay gain values are stored in dB in Q8.8 format (maybe Q7.9 or relative to the max value for the bitdepth is better ?).[[BR]]
 
 
@@ -132 +123 @@
 - The first 2 values are stored using the same code as the block length code.[[BR]]
 - The next values are coded as :[[BR]]
-code = value(n) - 2*value(n-1) + value(n-2)[[BR]]
-1 bit is sent for code sign, and the absolute value of code is sent as golomb code with k=10. A log code, as Fibonacci or Elias may be better, but golomb is easier to implement.
-
+{{{
+code = value(n) - 2*value(n-1) + value(n-2)
+code <<= 1;
+if (code < 0)
+  code = -code | 1;
+}}}
+code is sent as [http://en.wikipedia.org/wiki/Golomb_code golomb code] with M = 2^12^.