Quiet Frame Decompress: Difference between revisions

Revision as of 19:06, 16 March 2025

EditDate	2025-03-16

Related Threads:

Page created to understand how fLaC decompresses the 0 Quiet Frame so it can be incorporated into analAI

Key differences:

Issues:

Warmup does not appear in wave or raw file which I don't understand as I get the same warmup values in analAI as FLaC seems to produce.

Skip metadata not pertinent ^[1]

FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC
Line Number	Code Package	Module	Value	Opertion Description
1047	SDC	Find Metadata	0xFFF8	FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC FFF8
1071	SDC	stream decoder process	0xFFF8	FLAC__stream_decoder_process_until_end_of_stream
2041	SDC	read_frame	Unk	read_frame_(FLAC__StreamDecoder decoder, FLAC__bool got_a_frame, FLAC__bool do_full_decode)
350	BRC	FLAC__bitreader_reset_read_crc16	Unk	(FLAC__BitReader *br, FLAC__uint16 seed)
2277	SDC	read_frame_header_	Unk	read_frame_header_(FLAC__StreamDecoder *decoder)byte.
381	BDC	FLAC__bitreader_is_consumed_byte_aligned	0	(const FLAC__BitReader *br)
2319	SDC	read in the raw header as bytes so we can CRC it, and parse it on the way	if(!FLAC__bitreader_read_raw_uint32(decoder->private_->input, &x, 8))
418	BDC	FLAC__bitreader_read_raw_uint32	variables below	(FLAC__BitReader br, FLAC__uint32 val, uint32_t bits)

Read Frame Header Metadata

Starting at 0x_1192 FFF8 C38C

& value 007F

0b_1111 1111 1111 10 Frame Header sync'. 14 bits
0b_0 mandatory 0 value Validation Bit 15
0b_0 0 = fixed blocking strategy Fixed Blocks or Not Bit 16
0b_1100 0x_C 12-8 = 4 so 2 to the 4th power = 16 time 256 = 4096 samples. ( 2358 SDC read frame header) frame blocksize
0b_0011 0x3 3 sample rate 192,000 ( 2379 SDC read frame header) samplerate'
0b1010 & 0b0111 = Case 2 FLAC__CHANNEL_ASSIGNMENT_MID_SIDE Channel Handling
0b110 = C 24 bits per sample bps
0b_0 Mandatory 0. Validation

32 bits consumed.

Variables
Variable	Decimal	Hex	Location Flac File
Bits	8	8
br->word		0xfff8c3ac005e	1192
br->consumed_bits	32	0x20

@@ Line 33: / Line 33: @@
 |}
-into analQuiet.flac 0xfff8c3ac005e
+ Read Frame Header Metadata
-* FFF8C3 Frame Sync for 192,000hz sample rate 24 bit sample size
+Starting at 0x_1192 FFF8 C38C
-* Channel selection for sample compression
+ & value 007F
-** 8 = Left Side
+* 0b_1111 1111 1111 10 Frame Header ''sync'''. 14 bits
-** '''A = Mid-side''' Key difference
+* 0b_0 mandatory 0 value  ''Validation'' Bit 15
+* 0b_0 0 = fixed blocking strategy '''Fixed Blocks or Not''' Bit 16
+* 0b_1100 0x_C 12-8 = 4  so 2 to the 4th power = 16 time 256 = 4096 samples. ( 2358 SDC read frame header) '''frame blocksize'''
+* 0b_0011 0x3 3 sample rate 192,000 ( 2379 SDC read frame header) ''samplerate'''
+* 0b1010 & 0b0111 = Case 2 FLAC__CHANNEL_ASSIGNMENT_MID_SIDE '''Channel Handling'''
+* 0b110 = C 24 bits per sample ''bps''
+* 0b_0  Mandatory 0.  ''Validation''
+''32 bits consumed.''
 {| class="wikitable" style="margin:auto"
 |+ Variables