ttml/ebu-ttd import: fix first sample duration when ts_begin is not zero as the container imposes #192
ttml/ebu-ttd import: fix first sample duration when ts_begin is not zero as the container imposes
#192

canatella/gpac,canatella/gpac,canatella/gpac,canatella/gpac,canatella/gpac,canatella/gpac,canatella/gpac