[FFmpeg-devel] [PATCH v2] avcodec/videotoolbox: fix decoding of some hevc videos
Aman Gupta
ffmpeg at tmm1.net
Thu May 17 23:19:40 EEST 2018
From: Aman Gupta <aman at tmm1.net>
See https://s3.amazonaws.com/tmm1/videotoolbox/germany-hevc-zdf.ts
This moves the hw_frames_ctx reference from the AVFrame to a new
VTHWFrame which now holds both the CVPixelBufferRef and the AVBuffer.
Previously we would set the hw_frames_context on the AVFrame directly,
but on some videos the HEVC decoder would copy and move frames around
to reorder them, and in the process could accidentally free the
hw_frames_ctx, such that it was NULL by the time videotoolbox_postproc_frame()
got called. This appears to be a bug specific to the HEVC decoder, but
after several days of debugging I was unable to figure out where
the memory management issue is occurring.
This patch works around the issue by assigning hw_frames_ctx only once
the AVFrame is about to returned to the user. Fixes playback of the
HEVC sample linked above on both macOS and iOS.
Signed-off-by: Aman Gupta <aman at tmm1.net>
---
libavcodec/videotoolbox.c | 67 +++++++++++++++++++++++++----------------------
1 file changed, 35 insertions(+), 32 deletions(-)
diff --git a/libavcodec/videotoolbox.c b/libavcodec/videotoolbox.c
index fe5c9004b4..ac45e23c16 100644
--- a/libavcodec/videotoolbox.c
+++ b/libavcodec/videotoolbox.c
@@ -46,10 +46,16 @@ enum { kCMVideoCodecType_HEVC = 'hvc1' };
#define VIDEOTOOLBOX_ESDS_EXTRADATA_PADDING 12
+typedef struct VTHWFrame {
+ CVPixelBufferRef pixbuf;
+ AVBufferRef *hw_frames_ctx;
+} VTHWFrame;
+
static void videotoolbox_buffer_release(void *opaque, uint8_t *data)
{
- CVPixelBufferRef cv_buffer = *(CVPixelBufferRef *)data;
- CVPixelBufferRelease(cv_buffer);
+ VTHWFrame *ref = (VTHWFrame *)data;
+ av_buffer_unref(&ref->hw_frames_ctx);
+ CVPixelBufferRelease(ref->pixbuf);
av_free(data);
}
@@ -76,22 +82,29 @@ static int videotoolbox_buffer_copy(VTContext *vtctx,
static int videotoolbox_postproc_frame(void *avctx, AVFrame *frame)
{
- CVPixelBufferRef ref = *(CVPixelBufferRef *)frame->buf[0]->data;
+ VTHWFrame *ref = (VTHWFrame *)frame->buf[0]->data;
- if (!ref) {
+ if (!ref->pixbuf) {
av_log(avctx, AV_LOG_ERROR, "No frame decoded?\n");
av_frame_unref(frame);
return AVERROR_EXTERNAL;
}
- frame->data[3] = (uint8_t*)ref;
+ frame->data[3] = (uint8_t*)ref->pixbuf;
+
+ if (ref->hw_frames_ctx) {
+ av_buffer_unref(&frame->hw_frames_ctx);
+ frame->hw_frames_ctx = av_buffer_ref(ref->hw_frames_ctx);
+ if (!frame->hw_frames_ctx)
+ return AVERROR(ENOMEM);
+ }
return 0;
}
int ff_videotoolbox_alloc_frame(AVCodecContext *avctx, AVFrame *frame)
{
- size_t size = sizeof(CVPixelBufferRef);
+ size_t size = sizeof(VTHWFrame);
uint8_t *data = NULL;
AVBufferRef *buf = NULL;
int ret = ff_attach_decode_data(frame);
@@ -318,26 +331,6 @@ CFDataRef ff_videotoolbox_hvcc_extradata_create(AVCodecContext *avctx)
return data;
}
-static int videotoolbox_set_frame(AVCodecContext *avctx, AVFrame *frame)
-{
- VTContext *vtctx = avctx->internal->hwaccel_priv_data;
- if (!frame->buf[0] || frame->data[3]) {
- av_log(avctx, AV_LOG_ERROR, "videotoolbox: invalid state\n");
- av_frame_unref(frame);
- return AVERROR_EXTERNAL;
- }
-
- CVPixelBufferRef *ref = (CVPixelBufferRef *)frame->buf[0]->data;
-
- if (*ref)
- CVPixelBufferRelease(*ref);
-
- *ref = vtctx->frame;
- vtctx->frame = NULL;
-
- return 0;
-}
-
int ff_videotoolbox_h264_start_frame(AVCodecContext *avctx,
const uint8_t *buffer,
uint32_t size)
@@ -446,11 +439,21 @@ static int videotoolbox_buffer_create(AVCodecContext *avctx, AVFrame *frame)
int width = CVPixelBufferGetWidth(pixbuf);
int height = CVPixelBufferGetHeight(pixbuf);
AVHWFramesContext *cached_frames;
+ VTHWFrame *ref;
int ret;
- ret = videotoolbox_set_frame(avctx, frame);
- if (ret < 0)
- return ret;
+ if (!frame->buf[0] || frame->data[3]) {
+ av_log(avctx, AV_LOG_ERROR, "videotoolbox: invalid state\n");
+ av_frame_unref(frame);
+ return AVERROR_EXTERNAL;
+ }
+
+ ref = (VTHWFrame *)frame->buf[0]->data;
+
+ if (ref->pixbuf)
+ CVPixelBufferRelease(ref->pixbuf);
+ ref->pixbuf = vtctx->frame;
+ vtctx->frame = NULL;
// Old API code path.
if (!vtctx->cached_hw_frames_ctx)
@@ -482,9 +485,9 @@ static int videotoolbox_buffer_create(AVCodecContext *avctx, AVFrame *frame)
vtctx->cached_hw_frames_ctx = hw_frames_ctx;
}
- av_buffer_unref(&frame->hw_frames_ctx);
- frame->hw_frames_ctx = av_buffer_ref(vtctx->cached_hw_frames_ctx);
- if (!frame->hw_frames_ctx)
+ av_buffer_unref(&ref->hw_frames_ctx);
+ ref->hw_frames_ctx = av_buffer_ref(vtctx->cached_hw_frames_ctx);
+ if (!ref->hw_frames_ctx)
return AVERROR(ENOMEM);
return 0;
--
2.14.2
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