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mpeg2dec: drop B-frame on open gop

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Enhance open gop detection to drop B-frame which are invalid
before the first reference frame.

In stream such
gst-integration-testsuites/medias/defaults/mxf/op2b-mpeg2-wave_hd.mxf,
the two first frames must be dropped as we detect an open GOP situation
but in another media, such as http://col.la/1920X1080IXDCAMEX5MIN, the
first frames should not be dropped as we are in a closed GOP situation.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-ugly/-/merge_requests/84>
This commit is contained in:
Stéphane Cerveau 2021-07-28 11:49:16 +02:00
parent cc1a7e2c4d
commit fbe2ea6e38
1 changed files with 12 additions and 4 deletions
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16
ext/mpeg2dec/gstmpeg2dec.c
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@ -967,6 +967,8 @@ handle_slice (GstMpeg2dec * mpeg2dec, const mpeg2_info_t * info)
GstVideoCodecFrame *frame;
const mpeg2_picture_t *picture;
gboolean key_frame = FALSE;
gboolean bidirect_frame = FALSE;
gboolean closed_gop = FALSE;
GST_DEBUG_OBJECT (mpeg2dec,
"fbuf:%p display_picture:%p current_picture:%p fbuf->id:%d",
@ -981,6 +983,9 @@ handle_slice (GstMpeg2dec * mpeg2dec, const mpeg2_info_t * info)
goto no_frame;
picture = info->display_picture;
key_frame = (picture->flags & PIC_MASK_CODING_TYPE) == PIC_FLAG_CODING_TYPE_I;
bidirect_frame =
(picture->flags & PIC_MASK_CODING_TYPE) == PIC_FLAG_CODING_TYPE_B;
closed_gop = (info->gop->flags & GOP_FLAG_CLOSED_GOP);
GST_DEBUG_OBJECT (mpeg2dec, "picture flags: %d, type: %d, keyframe: %d",
picture->flags, picture->flags & PIC_MASK_CODING_TYPE, key_frame);
@ -999,11 +1004,14 @@ handle_slice (GstMpeg2dec * mpeg2dec, const mpeg2_info_t * info)
return ret;
}
/* Skip B-frames if GOP is not closed and waiting for the first keyframe. */
if (mpeg2dec->discont_state != MPEG2DEC_DISC_NONE) {
GST_DEBUG_OBJECT (mpeg2dec, "dropping buffer, discont state %d",
mpeg2dec->discont_state);
ret = gst_video_decoder_drop_frame (GST_VIDEO_DECODER (mpeg2dec), frame);
return ret;
if (bidirect_frame && !closed_gop) {
GST_DEBUG_OBJECT (mpeg2dec, "dropping buffer, discont state %d",
mpeg2dec->discont_state);
ret = gst_video_decoder_drop_frame (GST_VIDEO_DECODER (mpeg2dec), frame);
return ret;
}
}
/* do cropping if the target region is smaller than the input one */