ffmpeg has existing support for MLV raw video files; libavformat/mlvdec.c.
Since this was added, MLV has been extended to support LJ92 compressed
image data. These patches build on lossless DNG support in 7.2-dev to
enable handling LJ92 MLV via existing libavcodec/mjpegdec.c code.
I can provide MLV sample files if desired, being raw video these tend to be
large.
Thanks to JEEB and Lynne for help via IRC.
From 94ce8688af3a2c748de4021687b5d45a0a6b7be2 Mon Sep 17 00:00:00 2001
From: stephen-e <33672591+reticulatedpi...@users.noreply.github.com>
Date: Mon, 21 Oct 2024 16:35:49 +0100
Subject: [PATCH 2/2] avformat/mlvdec: add LJ92 support
MLV files can contain LJ92 compressed raw video data.
MJPEG codec can be used to handle these.
---
libavformat/mlvdec.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/libavformat/mlvdec.c b/libavformat/mlvdec.c
index 1a6d38f37c..2eb21a3aab 100644
--- a/libavformat/mlvdec.c
+++ b/libavformat/mlvdec.c
@@ -44,8 +44,9 @@
#define MLV_AUDIO_CLASS_WAV 1
-#define MLV_CLASS_FLAG_DELTA 0x40
#define MLV_CLASS_FLAG_LZMA 0x80
+#define MLV_CLASS_FLAG_DELTA 0x40
+#define MLV_CLASS_FLAG_LJ92 0x20
typedef struct {
AVIOContext *pb[101];
@@ -298,9 +299,12 @@ static int read_header(AVFormatContext *avctx)
if ((mlv->class[0] & (MLV_CLASS_FLAG_DELTA|MLV_CLASS_FLAG_LZMA)))
avpriv_request_sample(avctx, "compression");
vst->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
- switch (mlv->class[0] & ~(MLV_CLASS_FLAG_DELTA|MLV_CLASS_FLAG_LZMA)) {
+ switch (mlv->class[0] & ~(MLV_CLASS_FLAG_DELTA|MLV_CLASS_FLAG_LZMA|MLV_CLASS_FLAG_LJ92)) {
case MLV_VIDEO_CLASS_RAW:
- vst->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
+ if (mlv->class[0] & MLV_CLASS_FLAG_LJ92)
+ vst->codecpar->codec_id = AV_CODEC_ID_MJPEG;
+ else
+ vst->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
break;
case MLV_VIDEO_CLASS_YUV:
vst->codecpar->format = AV_PIX_FMT_YUV420P;
--
2.45.2
From bda19449cce6ae028ef751f0f4f21da63214ab3f Mon Sep 17 00:00:00 2001
From: stephen-e <33672591+reticulatedpi...@users.noreply.github.com>
Date: Mon, 21 Oct 2024 16:32:01 +0100
Subject: [PATCH 1/2] avcodec/mjpegdec: set bayer flag based on pix_fmt
dng_decode_jpeg() does this directly in tiff.c,
this change allows signalling via the pixel format
(to support LJ92 compressed raw video in MLV containers,
which is the next commit).
---
libavcodec/mjpegdec.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 86ec58713c..9c990f3e03 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -409,6 +409,15 @@ int ff_mjpeg_decode_sof(MJpegDecodeContext *s)
return AVERROR_PATCHWELCOME;
}
+ // If the given pixel format is Bayer, set the flag (this makes LJ92 MLV files work)
+ s->pix_desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
+ if (!s->pix_desc) {
+ av_log(s->avctx, AV_LOG_ERROR, "Could not get a pixel format descriptor.\n");
+ return AVERROR_BUG;
+ }
+ if (s->pix_desc->flags & AV_PIX_FMT_FLAG_BAYER)
+ s->bayer = 1;
+
if (s->bayer) {
if (nb_components == 2) {
/* Bayer images embedded in DNGs can contain 2 interleaved components and the
@@ -718,12 +727,6 @@ int ff_mjpeg_decode_sof(MJpegDecodeContext *s)
s->avctx->pix_fmt = AV_PIX_FMT_GRAY16;
}
- s->pix_desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
- if (!s->pix_desc) {
- av_log(s->avctx, AV_LOG_ERROR, "Could not get a pixel format descriptor.\n");
- return AVERROR_BUG;
- }
-
if (s->avctx->pix_fmt == s->hwaccel_sw_pix_fmt && !size_change) {
s->avctx->pix_fmt = s->hwaccel_pix_fmt;
} else {
--
2.45.2
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