Заголовок фрейма
| +0 |
FFh |
| +1 |
Bit:
| 0 |
Protection Bit (CRC):
|
| 1, 2 |
Layer:
| 1 |
Layer III |
| 2 |
Layer II |
| 3 |
Layer I |
|
| 3, 4 |
MPEG version:
| 0 |
MPEG 2.5 (44100 KHz) |
| 2 |
MPEG 2.0 (22050 KHz) |
| 3 |
MPEG 1.0 (11025 KHz) |
|
| 5 - 7 |
установлены (1) |
|
| +2 |
Bit:
| 0 |
Private |
| 1 |
Padding Bit |
| 2, 3 |
Sample Frequency:
| 0 |
0 - 44100 KHz |
| 1 |
48000 KHz |
| 2 |
32000 KHz |
|
| 4 - 7 |
Bitrate Index (в таблице значения Bitrate в kbps)
| Bitrate Index |
Layer |
| I |
II |
III |
| 1 |
32 |
32 |
32 |
| 2 |
64 |
48 |
40 |
| 3 |
96 |
56 |
48 |
| 4 |
128 |
64 |
56 |
| 5 |
160 |
80 |
64 |
| 6 |
192 |
96 |
80 |
| 7 |
224 |
112 |
96 |
| 8 |
256 |
128 |
112 |
| 9 |
288 |
160 |
128 |
| 10 |
320 |
192 |
160 |
| 11 |
352 |
224 |
192 |
| 12 |
384 |
256 |
224 |
| 13 |
416 |
320 |
256 |
| 14 |
448 |
384 |
320 |
|
|
| +3 |
Bit:
| 0, 1 |
Emphasis:
| 0 |
None |
| 1 |
50/15 microsec |
| 2 |
Dunno |
| 3 |
CITT j.17 |
|
| 2 |
Original |
| 3 |
Copyright |
| 4, 5 |
Mode Extension |
| 6, 7 |
Mode:
| 0 |
Stereo |
| 1 |
Joint Stereo |
| 2 |
Dual Channel |
| 3 |
Single Channel |
|
|
Длина фрейма (Layer 2,3)
FrameSize = 144 * bps / Sample_Frequency + Padding_Bit
Extended Header (Layer 3)
| MPEG version |
Stereo |
Mono |
| 1.0 |
32 |
17 |
| 2.x |
17 |
09 |
ID3TAG
| -128 |
Title[30] |
| Artist[30] |
| Album[30] |
| Year[4] |
| Comment[30] |
| Genre[1] |
DIDTAG
Variable ID Tag for MPEG3 Files (DIDTAG) Ver 1.00 Dez. 1997
| Field |
Length |
Comment |
| 1. |
6 Bytes |
"DIDTAG" |
| 2. |
1 Byte |
Length of title string |
| 3. |
x Byte |
Title (Length: 2. Field) |
| 4. |
1 Byte |
Length of artist string |
| 5. |
x Byte |
Artist (Length: 4. Field) |
| 6. |
1 Byte |
Length of album string |
| 7. |
x Byte |
Album (Length: 6. Field) |
| 8. |
4 Bytes |
Year |
| 9. |
1 Byte |
Length of software string |
| 10. |
x Byte |
Software used for sampling (Length: 9. Field) |
| 11. |
1 Byte |
Length of sampled-by string |
| 12. |
x Byte |
Track sampled by... (Length: 11. Field) |
| 13. |
1 Byte |
Length of comment field |
| 14. |
x Byte |
Comments (Length: 13. Field) |
| 15. |
1 Byte |
Length of Genre field |
| 16. |
x Byte |
Genre - use as you like, but don't make up too much new. (Length: 15.
Field) |
| 17. |
Word (2 Bytes) |
Length of whole tag |
| 18. |
6 Bytes |
"ENDTAG" |
If you read a file, first seek end-128 and look if the file has got an ID3
Tag. (As your Software probably already does.) If, seek back 6 Bytes and look for
"ENDTAG", you then can process my new tag. If there is no "ENDTAG", just
process the ID3 Tag. If there is no ID3 Tag, there is the chance there is a DIDTAG, so
seek end-6 and check for "ENDTAG"....