I found two problems with decoding of DNxHD encoded videos in MXF container.
1. The DNxHD codec signature in libavformat/mxf.c is wrong.
2. Frame height is calculated incorrectly for interlaced videos. What's
stored in PictureEssenceDescriptor in MXF is not a frame height but
field height.
This is a general problem that should affect other codecs. I checked
how D-10 (IMX) in MXF container ends up being handled correctly, and it
turned out it's because of stream parsing.
The patches fixing the decoding problems are attached. Note that I
didn't look at MXF encoding, which might or might not be affected by
problem 2.
--
Joseph Artsimovich
Software Developer
MirriAd Ltd
>From 47cbc31c9b4584a0ce6bc01a102837ba8012afb5 Mon Sep 17 00:00:00 2001
From: Joseph Artsimovich <[email protected]>
Date: Wed, 26 Oct 2011 15:06:59 +0100
Subject: [PATCH 1/2] Don't confuse frame height with field height in MXF
decoder.
---
libavformat/mxfdec.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index 76a8329..78dbc27 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -95,6 +95,7 @@ typedef struct {
AVRational aspect_ratio;
int width;
int height;
+ int frame_layout;
int channels;
int bits_per_sample;
UID *sub_descriptors_refs;
@@ -585,6 +586,9 @@ static int mxf_read_generic_descriptor(void *arg,
AVIOContext *pb, int tag, int
case 0x3202:
descriptor->height = avio_rb32(pb);
break;
+ case 0x320C:
+ descriptor->frame_layout = avio_r8(pb);
+ break;
case 0x320E:
descriptor->aspect_ratio.num = avio_rb32(pb);
descriptor->aspect_ratio.den = avio_rb32(pb);
@@ -817,7 +821,9 @@ static int mxf_parse_structural_metadata(MXFContext *mxf)
if (st->codec->codec_id == CODEC_ID_NONE)
st->codec->codec_id = container_ul->id;
st->codec->width = descriptor->width;
- st->codec->height = descriptor->height;
+ st->codec->height = descriptor->height; /* field height, not frame
height */
+ if (descriptor->frame_layout == 1) /* interlaced */
+ st->codec->height *= 2;
if (st->codec->codec_id == CODEC_ID_RAWVIDEO)
st->codec->pix_fmt = descriptor->pix_fmt;
st->need_parsing = AVSTREAM_PARSE_HEADERS;
--
1.7.5.4
>From fd7dbaf0d4acdccf231fe4a87ca0f9f971051b8e Mon Sep 17 00:00:00 2001
From: Joseph Artsimovich <[email protected]>
Date: Wed, 26 Oct 2011 15:08:46 +0100
Subject: [PATCH 2/2] Fix incorrect DNxHD codec signature in MXF container.
---
libavformat/mxf.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/libavformat/mxf.c b/libavformat/mxf.c
index 029486f..3d5c65d 100644
--- a/libavformat/mxf.c
+++ b/libavformat/mxf.c
@@ -41,7 +41,7 @@ const MXFCodecUL ff_mxf_codec_uls[] = {
{ {
0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x01,0x04,0x01,0x02,0x02,0x02,0x01,0x02,0x00
}, 13, CODEC_ID_DVVIDEO }, /* DV25 IEC PAL */
{ {
0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x07,0x04,0x01,0x02,0x02,0x03,0x01,0x01,0x00
}, 14, CODEC_ID_JPEG2000 }, /* JPEG2000 Codestream */
{ {
0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x01,0x04,0x01,0x02,0x01,0x7F,0x00,0x00,0x00
}, 13, CODEC_ID_RAWVIDEO }, /* Uncompressed */
- { {
0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x01,0x04,0x01,0x02,0x02,0x03,0x02,0x00,0x00
}, 14, CODEC_ID_DNXHD }, /* SMPTE VC-3/DNxHD */
+ { {
0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x01,0x04,0x01,0x02,0x02,0x71,0x00,0x00,0x00
}, 13, CODEC_ID_DNXHD }, /* SMPTE VC-3/DNxHD */
/* SoundEssenceCompression */
{ {
0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x01,0x04,0x02,0x02,0x01,0x00,0x00,0x00,0x00
}, 13, CODEC_ID_PCM_S16LE }, /* Uncompressed */
{ {
0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x01,0x04,0x02,0x02,0x01,0x7F,0x00,0x00,0x00
}, 13, CODEC_ID_PCM_S16LE },
--
1.7.5.4
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