oyvindln/vhs-decode

Cannot decode Betamax if compressed

Closed this issue · 2 comments

davidvankemenade commented

Bug Description

Compressed Betamax capture cannot be decoded, will yield continuous "Unable to determine start of field - dropping field".

Steps to Reproduce

  1. Capture 16-bit .raw file using DdD
  2. Compress to 16-bit FLAC:

decode.exe vhs --use_saved_levels --level_detect_divisor 2 --fallback_vsync --chroma_trap --recheck_phase --pal --threads 4 --tape_format Betamax capture.raw outputname

Expected Behavior

16-bit FLAC from Betamax would be decoded normally.

Actual Behavior

  1. Console outputs continous "Unable to determine start of field - dropping field"
  2. Log file contains repetition of:

2023-11-04 19:19:22,518 - lddecode - DEBUG - VBI EQ serration pulses search failed (using fallback logic)
2023-11-04 19:19:22,569 - lddecode - DEBUG - Level detection failed - sync or blank is None
2023-11-04 19:19:22,593 - lddecode - DEBUG - No vsync found!
2023-11-04 19:19:22,595 - lddecode - ERROR - Unable to determine start of field - dropping field

  1. No JSON file is created
  2. .tbc and chroma.tbc files are zero bytes

Environment

  • vhs-decode.exe 0.2.2 (Windows)
  • latest commit (Ubuntu) - no version number shown

Additional Information

  • I can only get 16-bit Betamax captures working by working directly off uncompressed .raw file AND omitting --no_resample
  • When using (S)VHS, there is no problem using 16-bit compressed FLAC files as input
davidvankemenade commented

Apologies, just after submitting this I found that I inadvertently dealt with a compressed Video8 capture instead of the Betamax one. This explains why the syncs couldn't be found.

harrypm commented

I'll close this then.

  • 👍1