decoder: h264: detect incorrectly paired fields in frames.

When a DPB flush is required, e.g. at a natural and of stream or issued
explicitly through an IDR, try to detect any frame left in the DPB that
is interlaced but does not contain two decoded fields. In that case, mark
the picture as having a single field only.

This avoids a hang while decoding tv_cut.mkv.

diff --git a/gst-libs/gst/vaapi/gstvaapidecoder_h264.c b/gst-libs/gst/vaapi/gstvaapidecoder_h264.c
index 8297e78..6b57fa6 100644 (file)
--- a/gst-libs/gst/vaapi/gstvaapidecoder_h264.c
+++ b/gst-libs/gst/vaapi/gstvaapidecoder_h264.c
@@ -894,6 +894,20 @@ dpb_clear(GstVaapiDecoderH264 *decoder, GstVaapiPictureH264 *picture)
 static void
 dpb_flush(GstVaapiDecoderH264 *decoder, GstVaapiPictureH264 *picture)
 {
+    GstVaapiDecoderH264Private * const priv = &decoder->priv;
+    guint i;
+
+    /* Detect broken frames and mark them as having a single field if
+       needed */
+    for (i = 0; i < priv->dpb_count; i++) {
+        GstVaapiFrameStore * const fs = priv->dpb[i];
+        if (!fs->output_needed || gst_vaapi_frame_store_is_complete(fs))
+            continue;
+        GST_VAAPI_PICTURE_FLAG_SET(fs->buffers[0],
+            GST_VAAPI_PICTURE_FLAG_ONEFIELD);
+    }
+
+    /* Output any frame remaining in DPB */
     while (dpb_bump(decoder, picture))
         ;
     dpb_clear(decoder, picture);