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| author | Reynaldo H. Verdejo Pinochet <reynaldo@osg.samsung.com> | 2016-01-22 18:26:01 -0800 |
|---|---|---|
| committer | Tim-Philipp Müller <tim@centricular.com> | 2016-03-02 23:36:20 +0000 |
| commit | ddfd731ea2bd147321a08f8f35e1fc6ebd11c5e5 (patch) | |
| tree | 296a23745cfe4dbe83a4a2dd6c94823aebbaa22e | |
| parent | 1960e1002fb4fa3c9afb3f0a46140beaa4947dcb (diff) | |
| download | gstreamer-plugins-base-ddfd731ea2bd147321a08f8f35e1fc6ebd11c5e5.tar.gz | |
typefind: strengthen check for valid H.263 picture layer
Avoids some false positives leading to miss identification:
* Prevent picture start code emulation for the first 2 bytes read
* Add check for valid "picture coding type" and "PB-frames mode" combination
Additionally, change name on confusingly named TR var to what
it is, the layer's PTYPE.
https://bugzilla.gnome.org/show_bug.cgi?id=693263
| -rw-r--r-- | gst/typefind/gsttypefindfunctions.c | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/gst/typefind/gsttypefindfunctions.c b/gst/typefind/gsttypefindfunctions.c index 4732c4e46..1e90f5546 100644 --- a/gst/typefind/gsttypefindfunctions.c +++ b/gst/typefind/gsttypefindfunctions.c @@ -2582,12 +2582,13 @@ static void h263_video_type_find (GstTypeFind * tf, gpointer unused) { DataScanCtx c = { 0, NULL, 0 }; - guint64 data = 0; + guint64 data = 0xffff; /* prevents false positive for first 2 bytes */ guint64 psc = 0; - guint8 tr = 0; + guint8 ptype = 0; guint format; guint good = 0; guint bad = 0; + guint pc_type, pb_mode; while (c.offset < H263_MAX_PROBE_LENGTH) { if (G_UNLIKELY (!data_scan_ctx_ensure_data (tf, &c, 4))) @@ -2598,16 +2599,21 @@ h263_video_type_find (GstTypeFind * tf, gpointer unused) psc = data & G_GUINT64_CONSTANT (0xfffffc0000); if (psc == 0x800000) { /* Found PSC */ - /* TR */ - tr = (data & 0x3fc) >> 2; + /* PTYPE */ + ptype = (data & 0x3fc) >> 2; /* Source Format */ - format = tr & 0x07; + format = ptype & 0x07; /* Now that we have a Valid PSC, check if we also have a valid PTYPE and the Source Format, which should range between 1 and 5 */ - if (((tr >> 6) == 0x2) && (format > 0 && format < 6)) - good++; - else + if (((ptype >> 6) == 0x2) && (format > 0 && format < 6)) { + pc_type = data & 0x02; + pb_mode = c.data[1] & 0x20 >> 4; + if (!pc_type && pb_mode) + bad++; + else + good++; + } else bad++; /* FIXME: maybe bail out early if we get mostly bad syncs ? */ |