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qtdemux: Validate matrix before doing simplified multiply

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The matrix multiplication makes some assumption about the element
values to simplify the math with fixpoint values. If this is allowed
for the given matrices is now checked first.

Then the debug output for matrix and a comment have been fixed.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8127>
This commit is contained in:
Jochen Henneberg 2024-12-18 08:44:30 +01:00 committed by GStreamer Marge Bot
parent 5c005733ea
commit d86f60ffdf
1 changed files with 53 additions and 16 deletions
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69
subprojects/gst-plugins-good/gst/isomp4/qtdemux.c
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@ -11416,16 +11416,43 @@ qtdemux_parse_transformation_matrix (GstQTDemux * qtdemux,
matrix[7] = gst_byte_reader_get_uint32_be_unchecked (reader); matrix[7] = gst_byte_reader_get_uint32_be_unchecked (reader);
matrix[8] = gst_byte_reader_get_uint32_be_unchecked (reader); matrix[8] = gst_byte_reader_get_uint32_be_unchecked (reader);
/* The 2.30 value conversion does not work for negative values */
GST_DEBUG_OBJECT (qtdemux, "Transformation matrix from atom %s", atom); GST_DEBUG_OBJECT (qtdemux, "Transformation matrix from atom %s", atom);
GST_DEBUG_OBJECT (qtdemux, "%u.%u %u.%u %u.%u", matrix[0] >> 16, GST_DEBUG_OBJECT (qtdemux, "%i.%u %i.%u %u.%u", (gint16) (matrix[0] >> 16),
matrix[0] & 0xFFFF, matrix[1] >> 16, matrix[1] & 0xFF, matrix[2] >> 16, matrix[0] & 0xFFFF, (gint16) (matrix[1] >> 16), matrix[1] & 0xFFFF,
matrix[2] & 0xFF); matrix[2] >> 30, matrix[2] & 0x3FFFFFFF);
GST_DEBUG_OBJECT (qtdemux, "%u.%u %u.%u %u.%u", matrix[3] >> 16, GST_DEBUG_OBJECT (qtdemux, "%i.%u %i.%u %u.%u", (gint16) (matrix[3] >> 16),
matrix[3] & 0xFFFF, matrix[4] >> 16, matrix[4] & 0xFF, matrix[5] >> 16, matrix[3] & 0xFFFF, (gint16) (matrix[4] >> 16), matrix[4] & 0xFFFF,
matrix[5] & 0xFF); matrix[5] >> 30, matrix[5] & 0x3FFFFFFF);
GST_DEBUG_OBJECT (qtdemux, "%u.%u %u.%u %u.%u", matrix[6] >> 16, GST_DEBUG_OBJECT (qtdemux, "%i.%u %i.%u %u.%u", (gint16) (matrix[6] >> 16),
matrix[6] & 0xFFFF, matrix[7] >> 16, matrix[7] & 0xFF, matrix[8] >> 16, matrix[6] & 0xFFFF, (gint16) (matrix[7] >> 16), matrix[7] & 0xFFFF,
matrix[8] & 0xFF); matrix[8] >> 30, matrix[8] & 0x3FFFFFFF);
return TRUE;
}
/* Check if all matrix elements are either 0, 1 or -1 */
static gboolean
qtdemux_transformation_matrix_is_simple (guint32 * m)
{
int i;
for (i = 0; i < 9; i++) {
switch (i) {
case 2:
case 5:
case 8:
/* 2.30 */
if (m[i] != 0U && m[i] != (1U << 30) && m[i] != (3U << 30))
return FALSE;
break;
default:
/* 16.16 */
if (m[i] != 0U && m[i] != (1U << 16) && m[i] != (G_MAXUINT16 << 16))
return FALSE;
break;
}
}
return TRUE; return TRUE;
} }
@ -11439,12 +11466,22 @@ qtdemux_mul_transformation_matrix (GstQTDemux * qtdemux,
#define QTADD_MATRIX(_a,_b) ((_a) + (_b) > 0 ? (1U << 16) : \ #define QTADD_MATRIX(_a,_b) ((_a) + (_b) > 0 ? (1U << 16) : \
((_a) + (_b) < 0) ? (G_MAXUINT16 << 16) : 0u) ((_a) + (_b) < 0) ? (G_MAXUINT16 << 16) : 0u)
c[2] = c[5] = c[6] = c[7] = 0; if (!qtdemux_transformation_matrix_is_simple (a) ||
c[0] = QTADD_MATRIX (QTMUL_MATRIX (a[0], b[0]), QTMUL_MATRIX (a[1], b[3])); !qtdemux_transformation_matrix_is_simple (b)) {
c[1] = QTADD_MATRIX (QTMUL_MATRIX (a[0], b[1]), QTMUL_MATRIX (a[1], b[4])); GST_WARNING_OBJECT (qtdemux,
c[3] = QTADD_MATRIX (QTMUL_MATRIX (a[3], b[0]), QTMUL_MATRIX (a[4], b[3])); "Cannot handle transform matrix with element values other than 0, 1 or -1");
c[4] = QTADD_MATRIX (QTMUL_MATRIX (a[3], b[1]), QTMUL_MATRIX (a[4], b[4])); /* Pretend to have an identity matrix in this case */
c[8] = a[8]; c[1] = c[2] = c[3] = c[5] = c[6] = c[7] = 0;
c[0] = c[4] = (1U << 16);
c[8] = (1 << 30);
} else {
c[2] = c[5] = c[6] = c[7] = 0;
c[0] = QTADD_MATRIX (QTMUL_MATRIX (a[0], b[0]), QTMUL_MATRIX (a[1], b[3]));
c[1] = QTADD_MATRIX (QTMUL_MATRIX (a[0], b[1]), QTMUL_MATRIX (a[1], b[4]));
c[3] = QTADD_MATRIX (QTMUL_MATRIX (a[3], b[0]), QTMUL_MATRIX (a[4], b[3]));
c[4] = QTADD_MATRIX (QTMUL_MATRIX (a[3], b[1]), QTMUL_MATRIX (a[4], b[4]));
c[8] = a[8];
}
} }
static void static void
@ -11456,7 +11493,7 @@ qtdemux_inspect_transformation_matrix (GstQTDemux * qtdemux,
* [d e f] * [d e f]
* [g h i] * [g h i]
* *
* This macro will only compare value abdegh, it expects cfi to have already * This macro will only compare value abde, it expects cfi to have already
* been checked * been checked
*/ */
#define QTCHECK_MATRIX(m,a,b,d,e) ((m)[0] == (a << 16) && (m)[1] == (b << 16) && \ #define QTCHECK_MATRIX(m,a,b,d,e) ((m)[0] == (a << 16) && (m)[1] == (b << 16) && \