Issue with timing (diagnosed, but not fixed) #456

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claunia · 2026-01-29T16:44:24Z

claunia commented

2026-01-29 16:44:24 +00:00

Originally created by @diksha90 on GitHub (Oct 27, 2018).

It is known that timing in our CEA-708 is different from the timing of CEA-708 in video player with a difference of a second or so and in general it's not critical error.
But sometimes the timing differs a lot - end of the time goes ahead ~10 seconds or so in different examples. This always happens due to this bug where window is undefined (decoder->current_window == -1) and it's col_count too: line (and line 129). It may be a one line fix or maybe hell with codecs, but I must sleep and somewhere else, so if you want we can fix it together.

ccextractor/src/lib_ccx/ccx_decoders_708.c
Line 1115 in 25a8b53
if (screen_content_changed && !_dtvcc_decoder_has_visible_windows(decoder))

In this line , although we check screen content and works correctly if there is any active window in decoder but current_window many times have value -1 and none of the windows are defined or active in decoder,

which causes above mentioned exception and also we cannot ignore content without defined windows, as I have tested we miss captions.
Therefore either we can store that data until a new window is defined or we can flush screen data before removing window.

This is just one instance , similar solution might be needed for handling this issue in other case .

Originally created by @diksha90 on GitHub (Oct 27, 2018). It is known that timing in our CEA-708 is different from the timing of CEA-708 in video player with a difference of a second or so and in general it's not critical error. But sometimes the timing differs a lot - end of the time goes ahead ~10 seconds or so in different examples. This always happens due to this bug where window is undefined (decoder->current_window == -1) and it's col_count too: line (and line 129). It may be a one line fix or maybe hell with codecs, but I must sleep and somewhere else, so if you want we can fix it together. **ccextractor/src/lib_ccx/ccx_decoders_708.c Line 1115 in 25a8b53 if (screen_content_changed && !_dtvcc_decoder_has_visible_windows(decoder))** In this line , although we check screen content and works correctly if there is any active window in decoder but current_window many times have value -1 and none of the windows are defined or active in decoder, which causes above mentioned exception and also we cannot ignore content without defined windows, as I have tested we miss captions. Therefore either we can store that data until a new window is defined or we can flush screen data before removing window. This is just one instance , similar solution might be needed for handling this issue in other case .

claunia referenced this issue

2026-01-29 17:00:45 +00:00

[PR #456] GCI: Updated README.md #1271

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Reference: starred/ccextractor#456