Review picks container creation time as start of video file instead of first embedded timestamo

[basrijn]

Ran into an interesting issue where a video scored on Laptop1 does no align with Laptop2. The actual timestamp for a given "frame" is different.

The video files I create have very accurate timestamps on each frame, but file creation is not very accurate. The current code:

_In FFReader.cpp:244–262 the native reader sets first_utc_us from (in priority):

1. com.crewtimer.first_utc_us custom tag (precise μs from capture software)
2. creation_time standard container tag (whole-second Unix μs via av_parse_time) ← added fallback
3. Otherwise first_utc_us stays 0 → FFReaderAPI.cpp:118 falls through to the pixel-row decode

And in FFReaderAPI.cpp:118 the code treats any non-zero first_utc_us as ground truth:
if (ffreader->getFirstUtcUs() != 0) {
tsMicro = firstUtcUs + pts*... // branch A — container-based
} else {
tsMicro = extractTimestampFromFrame(row 0/1) / 10 // branch B — pixel-decoded
}_

For my video files, the embedded timestamp is correct. I would actually suggest:

1. Embedded TS (tools that write the custom tag will likely not also write the embedded TS)
2. custom tag
3. creation_time