MAMEWorld Forums - EmuChat - chdman createcd <> chdman copy?

Let's take a disc from the PC Engine CD softlist:

Code:

Size      Time     Date       CRC32    Filename

    1863  23:32.00 1996-12-24 0814C835 Akumajou Dracula X - Chi no Rondo (SCD)(JPN).cue
 8620124  07:15.58 2013-02-13 C3E5039A Track01.wav
20785152  23:32.00 1996-12-24 E91084DA Track02.iso
18778412  07:16.02 2013-02-13 98CA1935 Track03.wav
11157932  07:16.03 2013-02-13 18B954FF Track04.wav
16974428  07:16.05 2013-02-13 7775E729 Track05.wav
14763548  07:16.07 2013-02-13 3370B385 Track06.wav
11404892  07:16.08 2013-02-13 4A1B5072 Track07.wav
31458044  07:16.16 2013-02-13 A874E614 Track08.wav
18270380  07:16.20 2013-02-13 2983CF25 Track09.wav
28346348  07:16.23 2013-02-13 DF874737 Track10.wav
17941100  07:16.26 2013-02-13 E25C01C7 Track11.wav
26542364  07:16.28 2013-02-13 9EF0F876 Track12.wav
26050796  07:16.30 2013-02-13 17B7E37C Track13.wav
38765708  07:16.35 2013-02-13 79A91938 Track14.wav
25658012  07:16.37 2013-02-13 5B78A7E6 Track15.wav
34506236  07:16.41 2013-02-13 19BEE4CA Track16.wav
15812540  07:16.43 2013-02-13 39A2B1E5 Track17.wav
18039884  07:16.45 2013-02-13 190A0049 Track18.wav
21170396  07:16.47 2013-02-13 0C5AEFD9 Track19.wav
42599468  07:16.52 2013-02-13 8136FD19 Track20.wav
44746844  07:16.56 2013-02-13 756E6C12 Track21.wav
20480000  23:32.00 1996-12-24 32DF5B20 Track22.iso

Converted to CHD v4 with for example 0.142 we get:

chdman - MAME Compressed Hunks of Data (CHD) manager 0.148 (Jan 24 2013)
Input file: Akumajou Dracula X - Chi no Rondo (SCD)(JPN)_v4.chd
File Version: 4
Logical size: 540,263,808 bytes
Hunk Size: 9,792 bytes
Total Hunks: 55,174
Unit Size: 2,448 bytes
Total Units: 220,696
Compression: zlib (Deflate)
CHD size: 434,855,210 bytes
Ratio: 80.5%
SHA1: bff01c949ae66b51797ec891befd91009591fbc1
Data SHA1: ba7117d84bbf76dc2025c843ba4438cb6ef9b35c

Converted from v4 to v5 using copy we get:

chdman - MAME Compressed Hunks of Data (CHD) manager 0.148 (Jan 24 2013)
Input file: Akumajou Dracula X - Chi no Rondo (SCD)(JPN)_v4_to_v5.chd
File Version: 5
Logical size: 540,263,808 bytes
Hunk Size: 9,792 bytes
Total Hunks: 55,174
Unit Size: 2,448 bytes
Total Units: 220,696
Compression: cdlz (CD LZMA), cdzl (CD Deflate), cdfl (CD FLAC)
CHD size: 269,785,489 bytes
Ratio: 49.9%
SHA1: bff01c949ae66b51797ec891befd91009591fbc1
Data SHA1: ba7117d84bbf76dc2025c843ba4438cb6ef9b35c

But creating the CHD with the original source or extracting the bin/cue files from the CHD we get:

chdman - MAME Compressed Hunks of Data (CHD) manager 0.148 (Jan 24 2013)
Input file: Akumajou Dracula X - Chi no Rondo (SCD)(JPN)_v5_from_extracted_chd.chd
File Version: 5
Logical size: 540,263,808 bytes
Hunk Size: 19,584 bytes
Total Hunks: 27,587
Unit Size: 2,448 bytes
Total Units: 220,696
Compression: cdlz (CD LZMA), cdzl (CD Deflate), cdfl (CD FLAC)
CHD size: 279,108,453 bytes
Ratio: 51.7%
SHA1: bff01c949ae66b51797ec891befd91009591fbc1
Data SHA1: ba7117d84bbf76dc2025c843ba4438cb6ef9b35c

In this case copying from v4 to v5 got 9MB smaller (because of the hunk size I suppose), but there are cases it happens quite the contrary. Not a problem because the content and extraction is consistent between any CHD. But for those keeping track of disk space or distribution methods should be aware.

Code:

Size       Time     Date       CRC32    Filename

434855210  07:24.05 2013-02-13 11B71FCA Akumajou Dracula X - Chi no Rondo (SCD)(JPN)_v4.chd
269785489  07:30.37 2013-02-13 E28FC844 Akumajou Dracula X - Chi no Rondo (SCD)(JPN)_v4_to_v5.chd
279108453  07:56.34 2013-02-13 F49A9560 Akumajou Dracula X - Chi no Rondo (SCD)(JPN)_v5_from_extracted_chd.chd
279108453  07:52.48 2013-02-13 F49A9560 Akumajou Dracula X - Chi no Rondo (SCD)(JPN)_v5_from_original.chd