Quiet Frame Decompress: Difference between revisions
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==Instruction trace flac for analQuiet.flac== | ==Instruction trace flac for analQuiet.flac== | ||
Skip metadata not pertinent <ref>(see [[FLAC Agent Build]] for metadata. Assuming equivalent in pertinent details.</ref> | Skip metadata not pertinent <ref>(see [[FLAC Agent Build]] for metadata. Assuming equivalent in pertinent details.</ref> | ||
==Sync Frame== | |||
{| class="wikitable" style="margin:auto" | {| class="wikitable" style="margin:auto" | ||
|+ FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC | |+ FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC | ||
| Line 41: | Line 41: | ||
|} | |} | ||
Read Frame Header Metadata | Read Frame Sync Fixed Header Channel Side | ||
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.'' | |||
{| class="wikitable" style="margin:auto" | |||
|+ Variables | |||
|- | |||
! Variable!! Decimal !! Hex !! Location Flac File | |||
|- | |||
|Bits || 8 || 8 | |||
|- | |||
|br->word || || 0xfff8c3ac005e || 1192 | |||
|- | |||
|br->consumed_bits || 32 || 0x20 | |||
|- | |||
|} | |||
==Read Frame Header== | |||
{| class="wikitable" style="margin:auto" | |||
|+ 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 Last Half Header Metadata | |||
Starting at 0x_1192 FFF8 C38C | Starting at 0x_1192 FFF8 C38C | ||
& value 007F | & value 007F | ||
Revision as of 00:49, 17 March 2025
| EditDate | 2025-03-16 |
|---|
Related Threads: FLAC Agent Build
Page created to understand how fLaC decompresses the 0 Quiet Frame so it can be incorporated into analAI
Key differences:
- Mid-side compression
Could well be the key
lossless transformation mid = (left + right)/2 and side = left − right.Web References https://www.reddit.com/r/audioengineering/comments/u2t2o4/questions about the way flac works relatively/
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.
Seems I may have to include additional step for mid side channel de-correlation. lossless transformation mid = (left + right)/2 and side = left − right. [1]. One sure issue with this is the side channel requires an extra bit (25 vs 24) which might explain the missed warmup values but right now I don’t think so. Either way it needs to be fixed.
Instruction trace flac for analQuiet.flac
Skip metadata not pertinent [2]
Sync Frame
| 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 Sync Fixed Header Channel Side
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.
| Variable | Decimal | Hex | Location Flac File |
|---|---|---|---|
| Bits | 8 | 8 | |
| br->word | 0xfff8c3ac005e | 1192 | |
| br->consumed_bits | 32 | 0x20 |
Read Frame Header
| 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 Last Half 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.
| Variable | Decimal | Hex | Location Flac File |
|---|---|---|---|
| Bits | 8 | 8 | |
| br->word | 0xfff8c3ac005e | 1192 | |
| br->consumed_bits | 32 | 0x20 |
References
- ↑ https://www.reddit.com/r/audioengineering/comments/u2t2o4/questions_about_the_way_flac_works_relatively/
- ↑ (see FLAC Agent Build for metadata. Assuming equivalent in pertinent details.