videosource: Only apply PAFF adjustment if the frame is marked as int…

…erlaced

Otherwise seeking can be jank in certain types of streams like open GOP HEVC
or MP4s with huge edit list trims a the very start.

Fixe FFMS#394.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

src/core/videosource.cpp

@@ -629,7 +629,7 @@ bool FFMS_VideoSource::DecodePacket(AVPacket *Packet) {
     // H.264 (PAFF) and HEVC can have one field per packet, and decoding delay needs
     // to be adjusted accordingly.
     if (CodecContext->codec_id == AV_CODEC_ID_H264 || CodecContext->codec_id == AV_CODEC_ID_HEVC) {
-        if (!PAFFAdjusted && DelayCounter > Delay && LastDecodedFrame->repeat_pict == 0 && Ret != 0) {
+        if (!PAFFAdjusted && DelayCounter > Delay && LastDecodedFrame->interlaced_frame == 1 && LastDecodedFrame->repeat_pict == 0 && Ret != 0) {
             int OldBFrameDelay = Delay - (CodecContext->thread_count - 1);
             Delay = 1 + OldBFrameDelay * 2 + (CodecContext->thread_count - 1);
             PAFFAdjusted = true;