docs: Clarify PS probe limit calculation (explain magic number)

[cfsmp3]

Summary

Replaces the magic number 49997 with 50000 - 3 and adds a clear inline comment explaining the PS stream probe limit calculation.

Changes

// Before:
} else {
    49997
}

// After:
} else {
    50000 - 3 // Don't scan huge buffers entirely; 50KB is enough
}

Why This Matters

The number 49997 appears arbitrary without context. The new code makes it clear that:

1. Why subtract 3: The loop checks startbytes[i], [i+1], [i+2], [i+3], so we must stop 3 bytes before the end to avoid out-of-bounds access

2. Why 50000: We cap the scan range for large buffers (no need to scan megabytes when 50KB is sufficient to detect the format)

3. Why saturating_sub: Handles edge case of tiny buffers (< 3 bytes) without underflow

Testing

• Build passes
• No functional change (50000 - 3 = 49997)

🤖 Generated with Claude Code

[ccextractor-bot]

CCExtractor CI platform finished running the test files on linux. Below is a summary of the test results, when compared to test for commit 618df18...:

Report Name	Tests Passed
Broken	13/13
CEA-708	14/14
DVB	7/7
DVD	3/3
DVR-MS	2/2
General	25/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	81/86
Teletext	21/21
WTV	13/13
XDS	34/34

Your PR breaks these cases:

• ccextractor --autoprogram --out=ttxt --latin1 --ucla dab1c1bd65...
• ccextractor --out=srt --latin1 --autoprogram 29e5ffd34b...
• ccextractor --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
• ccextractor --startcreditsnotbefore 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
• ccextractor --startcreditsnotafter 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
• ccextractor --startcreditsforatleast 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
• ccextractor --startcreditsforatmost 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...

Congratulations: Merging this PR would fix the following tests:

• ccextractor --autoprogram --out=srt --latin1 --quant 0 85271be4d2..., Last passed: Never
• ccextractor --out=spupng c83f765c66..., Last passed: Never

It seems that not all tests were passed completely. This is an indication that the output of some files is not as expected (but might be according to you).

Check the result page for more info.

[ccextractor-bot]

CCExtractor CI platform finished running the test files on windows. Below is a summary of the test results, when compared to test for commit 618df18...:

Report Name	Tests Passed
Broken	13/13
CEA-708	14/14
DVB	6/7
DVD	3/3
DVR-MS	2/2
General	25/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	80/86
Teletext	21/21
WTV	13/13
XDS	34/34

Your PR breaks these cases:

• ccextractor --program-number 1 c83f765c66...

NOTE: The following tests have been failing on the master branch as well as the PR:

• ccextractor --autoprogram --out=srt --latin1 --quant 0 85271be4d2..., Last passed:

  Test 7743

• ccextractor --autoprogram --out=ttxt --latin1 --ucla dab1c1bd65..., Last passed:

  Test 7743

• ccextractor --out=srt --latin1 --autoprogram 29e5ffd34b..., Last passed:

  Test 7743

• ccextractor --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed:

  Test 7743

• ccextractor --startcreditsnotbefore 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed:

  Test 7743

• ccextractor --startcreditsnotafter 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed:

  Test 7743

• ccextractor --startcreditsforatleast 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed:

  Test 7743

• ccextractor --startcreditsforatmost 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed:

  Test 7743

It seems that not all tests were passed completely. This is an indication that the output of some files is not as expected (but might be according to you).

Check the result page for more info.