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[FIX] Fix zero timestamps for GXF/MXF ancillary captions - #2390
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GXF and MXF hand caption data to process_data() as CCX_RAW_TYPE buffers with no video frames to anchor the timing. The caller has already run set_current_pts() for each packet, which sets pts_set to 1, and set_fts() only reaches MinPtsSet after seeing a video frame type, so the CCX_RAW_TYPE branch's "pts_set == 0" check never fired and min_pts was never established. fts stayed at 0, every GXF ancillary cue had zero length and SRT output was empty; MXF's first cues were stamped 0 until timing was set some seconds in. Establish min_pts in that branch whenever MinPtsSet hasn't been reached, and take it from timing->current_pts, which the caller has already rescaled to 90 kHz (data_node->pts is in GXF frame units).
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Repro instructions:
Generate the synthetic GXF from #2373 (
python3 gen_gxf_anc.py anc.gxf, one CEA-608 caption in an SMPTE 291 ancillary track) and runccextractor anc.gxf --out=srt -o out.srt. On master nothing is written ("Deleted empty output file"); with this PR:00:00:00,401 --> 00:00:02,468 GXF ANC TEST.GXF and MXF hand caption data to
process_data()asCCX_RAW_TYPEbuffers, with no video frames to anchor the timing. The caller has already calledset_current_pts()for the packet, which setspts_setto 1, andset_fts()only reaches MinPtsSet after seeing a video frame type — so theCCX_RAW_TYPEbranch'spts_set == 0check never fired andmin_ptswas never established.ftsstayed at 0, so every GXF ancillary cue had zero length and SRT output was empty; on MXF the first cues were stamped 0 until timing got established a few seconds in.This sets
min_ptsin that branch whenever MinPtsSet hasn't been reached, fromtiming->current_pts(already rescaled to 90 kHz by the caller;data_node->ptsis in GXF frame units).Only GXF and MXF reach this: the third
CCX_RAW_TYPEproducer, the FFmpeg integration, never sets a PTS, andCCX_RAWinputs (DVR-MS/ASF, RCWT) use a different branch.On a real MXF sample, the first two cues (608 at 0.001/2.486, 708 at 0.001/0.001) become 0.667/2.803 and 0.533/2.803, now agreeing between 608 and 708; all later cues are unchanged. Local GXF, MXF, raw, bin and RCWT samples are otherwise byte-identical to master, and ASan is clean.