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vtdec: handle non-consecutive GstBuffer input without copying

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CMBlockBuffer offers a model similar to GstBuffer, as it can
consist of multiple non-consecutive memory blocks.

Prior to this change, what we were doing was:

 1) Incorrect:

   CMBlockBufferCreateWithMemoryBlock does not copy the data,
   but we gst_buffer_unmap'd right away.

 2) Inefficient:

   If the GstBuffer consisted of non-contiguous memory blocks,
   gst_buffer_map resulted in malloc / memcpy.

With this change, we construct a CMBlockBuffer out of individual mapped
GstMemory objects. CMBlockBuffer is made to retain the GstMemory
objects (through the use of CMBlockBufferCustomBlockSource), so the
original GstBuffer can be unref'd.

https://bugzilla.gnome.org/show_bug.cgi?id=751241
This commit is contained in:
Ilya Konstantinov 2015-06-29 02:42:06 +03:00 committed by Nicolas Dufresne
parent c1906f1cfe
commit bfa054a733
1 changed files with 79 additions and 27 deletions
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106
sys/applemedia/vtdec.c
View file

@ -543,31 +543,92 @@ create_format_description_from_codec_data (GstVtdec * vtdec,
return NULL;
}
/* Custom FreeBlock function for CMBlockBuffer */
static void
cm_block_buffer_freeblock (void *refCon, void *doomedMemoryBlock,
size_t sizeInBytes)
{
GstMapInfo *info = (GstMapInfo *) refCon;
gst_memory_unmap (info->memory, info);
gst_memory_unref (info->memory);
g_slice_free (GstMapInfo, info);
}
static CMBlockBufferRef
cm_block_buffer_from_gst_buffer (GstBuffer * buf, GstMapFlags flags)
{
OSStatus status;
CMBlockBufferRef bbuf;
CMBlockBufferCustomBlockSource blockSource;
guint memcount, i;
/* Initialize custom block source structure */
blockSource.version = kCMBlockBufferCustomBlockSourceVersion;
blockSource.AllocateBlock = NULL;
blockSource.FreeBlock = cm_block_buffer_freeblock;
/* Determine number of memory blocks */
memcount = gst_buffer_n_memory (buf);
status = CMBlockBufferCreateEmpty (NULL, memcount, 0, &bbuf);
if (status != kCMBlockBufferNoErr) {
GST_ERROR ("CMBlockBufferCreateEmpty returned %d", (int) status);
return NULL;
}
/* Go over all GstMemory objects and add them to the CMBlockBuffer */
for (i = 0; i < memcount; ++i) {
GstMemory *mem;
GstMapInfo *info;
mem = gst_buffer_get_memory (buf, i);
info = g_slice_new (GstMapInfo);
if (!gst_memory_map (mem, info, flags)) {
GST_ERROR ("failed mapping memory");
g_slice_free (GstMapInfo, info);
gst_memory_unref (mem);
CFRelease (bbuf);
return NULL;
}
blockSource.refCon = info;
status =
CMBlockBufferAppendMemoryBlock (bbuf, info->data, info->size, NULL,
&blockSource, 0, info->size, 0);
if (status != kCMBlockBufferNoErr) {
GST_ERROR ("CMBlockBufferAppendMemoryBlock returned %d", (int) status);
gst_memory_unmap (mem, info);
g_slice_free (GstMapInfo, info);
gst_memory_unref (mem);
CFRelease (bbuf);
return NULL;
}
}
return bbuf;
}
static CMSampleBufferRef
cm_sample_buffer_from_gst_buffer (GstVtdec * vtdec, GstBuffer * buf)
{
OSStatus status;
CMBlockBufferRef bbuf = NULL;
CMSampleBufferRef sbuf = NULL;
GstMapInfo map;
CMSampleTimingInfo sample_timing;
CMSampleTimingInfo time_array[1];
g_return_val_if_fail (vtdec->format_description, NULL);
gst_buffer_map (buf, &map, GST_MAP_READ);
/* create a block buffer */
bbuf = cm_block_buffer_from_gst_buffer (buf, GST_MAP_READ);
if (bbuf == NULL) {
GST_ELEMENT_ERROR (vtdec, RESOURCE, FAILED, (NULL),
("failed creating CMBlockBuffer"));
return NULL;
}
/* create a block buffer, the CoreMedia equivalent of GstMemory */
status = CMBlockBufferCreateWithMemoryBlock (NULL,
map.data, (gint64) map.size, kCFAllocatorNull, NULL, 0, (gint64) map.size,
FALSE, &bbuf);
gst_buffer_unmap (buf, &map);
if (status != noErr)
goto block_error;
/* create a sample buffer, the CoreMedia equivalent of GstBuffer */
/* create a sample buffer */
if (GST_BUFFER_DURATION_IS_VALID (buf))
sample_timing.duration = CMTimeMake (GST_BUFFER_DURATION (buf), GST_SECOND);
else
@ -591,22 +652,13 @@ cm_sample_buffer_from_gst_buffer (GstVtdec * vtdec, GstBuffer * buf)
CMSampleBufferCreate (NULL, bbuf, TRUE, 0, 0, vtdec->format_description,
1, 1, time_array, 0, NULL, &sbuf);
CFRelease (bbuf);
if (status != noErr)
goto sample_error;
if (status != noErr) {
GST_ELEMENT_ERROR (vtdec, RESOURCE, FAILED, (NULL),
("CMSampleBufferCreate returned %d", (int) status));
return NULL;
}
out:
return sbuf;
block_error:
GST_ELEMENT_ERROR (vtdec, RESOURCE, FAILED, (NULL),
("CMBlockBufferCreateWithMemoryBlock returned %d", (int) status));
goto out;
sample_error:
GST_ELEMENT_ERROR (vtdec, RESOURCE, FAILED, (NULL),
("CMSampleBufferCreate returned %d", (int) status));
goto out;
}
static gint