avutil/frame: also align data pointers in av_frame_get_buffer()

This avoids unpleasant surprises to av_frame_get_buffer callers that explicitly specified 64-byte alignment and didn't get AVFrame.data pointers that are 64-byte aligned. For example, see https://github.com/sekrit-twc/zimg/issues/212 Although the zscale issue has already been resolved by other means it would still be prudent to improve the behavior of av_frame_get_buffer to fix any unknown and future instances of similar issues.

Pavel Koshevoy committed 1 year ago

Commit 46cb7b81 parent ea91d974 files · +25 −9Browse files

Unified · Split

4 files

doc/APIchanges +4 −0
libavutil/frame.c +16 −5
libavutil/frame.h +4 −3
libavutil/version.h +1 −1

doc/APIchanges+4−0

@@ -2,6 +2,10 @@ The last version increases of all libraries were on 2024-03-07 · 1 unmodified line
2		2
3	API changes, most recent first:	3	API changes, most recent first:
4		4
		5	2024-11-16 - xxxxxxxxxx - lavu 59.47.101 - frame.h
		6	av_frame_get_buffer() now also aligns the data pointers according to
		7	the requested alignment.
		8
5	2024-11-13 - xxxxxxxxxx - lavu 59.47.100 - channel_layout.h	9	2024-11-13 - xxxxxxxxxx - lavu 59.47.100 - channel_layout.h
6	Add AV_CHAN_BINAURAL_LEFT, AV_CHAN_BINAURAL_RIGHT	10	Add AV_CHAN_BINAURAL_LEFT, AV_CHAN_BINAURAL_RIGHT
7	Add AV_CH_BINAURAL_LEFT, AV_CH_BINAURAL_RIGHT	11	Add AV_CH_BINAURAL_LEFT, AV_CH_BINAURAL_RIGHT

libavutil/frame.c+16−5

                                          padded_height, linesizes)) < 0)
         return ret;
-    total_size = 4*plane_padding;
+    total_size = 4 * plane_padding + 4 * align;
     for (int i = 0; i < 4; i++) {
         if (sizes[i] > SIZE_MAX - total_size)
             return AVERROR(EINVAL);
     for (int i = 1; i < 4; i++) {
         if (frame->data[i])
             frame->data[i] += i * plane_padding;
+        frame->data[i] = (uint8_t *)FFALIGN((uintptr_t)frame->data[i], align);
     }
     frame->extended_data = frame->data;
 {
     int planar   = av_sample_fmt_is_planar(frame->format);
     int channels, planes;
+    size_t size;
     int ret;
     channels = frame->ch_layout.nb_channels;
             return ret;
     }
+    if (align <= 0)
+        align = ALIGN;
     if (planes > AV_NUM_DATA_POINTERS) {
         frame->extended_data = av_calloc(planes,
                                           sizeof(*frame->extended_data));
     } else
         frame->extended_data = frame->data;
+    if (frame->linesize[0] > SIZE_MAX - align)
+        return AVERROR(EINVAL);
+    size = frame->linesize[0] + (size_t)align;
     for (int i = 0; i < FFMIN(planes, AV_NUM_DATA_POINTERS); i++) {
-        frame->buf[i] = av_buffer_alloc(frame->linesize[0]);
+        frame->buf[i] = av_buffer_alloc(size);
         if (!frame->buf[i]) {
             av_frame_unref(frame);
             return AVERROR(ENOMEM);
         }
-        frame->extended_data[i] = frame->data[i] = frame->buf[i]->data;
+        frame->extended_data[i] = frame->data[i] =
+            (uint8_t *)FFALIGN((uintptr_t)frame->buf[i]->data, align);
     }
     for (int i = 0; i < planes - AV_NUM_DATA_POINTERS; i++) {
-        frame->extended_buf[i] = av_buffer_alloc(frame->linesize[0]);
+        frame->extended_buf[i] = av_buffer_alloc(size);
         if (!frame->extended_buf[i]) {
             av_frame_unref(frame);
             return AVERROR(ENOMEM);
         }
-        frame->extended_data[i + AV_NUM_DATA_POINTERS] = frame->extended_buf[i]->data;
+        frame->extended_data[i + AV_NUM_DATA_POINTERS] =
+            (uint8_t *)FFALIGN((uintptr_t)frame->extended_buf[i]->data, align);
     }
     return 0;

libavutil/frame.h+4−3

  *           cases.
  *
  * @param frame frame in which to store the new buffers.
- * @param align Required buffer size alignment. If equal to 0, alignment will be
+ * @param align Required buffer size and data pointer alignment. If equal to 0,
- *              chosen automatically for the current CPU. It is highly
+ *              alignment will be chosen automatically for the current CPU.
- *              recommended to pass 0 here unless you know what you are doing.
+ *              It is highly recommended to pass 0 here unless you know what
+ *              you are doing.
  *
  * @return 0 on success, a negative AVERROR on error.
  */

libavutil/version.h+1−1

@@ -80,7 +80,7 @@ · 79 unmodified lines
80		80
81	#define LIBAVUTIL_VERSION_MAJOR 59	81	#define LIBAVUTIL_VERSION_MAJOR 59
82	#define LIBAVUTIL_VERSION_MINOR 47	82	#define LIBAVUTIL_VERSION_MINOR 47
83	#define LIBAVUTIL_VERSION_MICRO 100	83	#define LIBAVUTIL_VERSION_MICRO 101
84		84
85	#define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \	85	#define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
86	LIBAVUTIL_VERSION_MINOR, \	86	LIBAVUTIL_VERSION_MINOR, \

avutil/frame: also align data pointers in av_frame_get_buffer()

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