[FFmpeg-devel] [PATCH] AVI metadata retrieval improvements
Michael Niedermayer
michaelni at gmx.at
Tue Mar 25 23:56:50 CET 2014
On Tue, Mar 25, 2014 at 10:07:24AM +0100, Thilo Borgmann wrote:
> Am 25.03.14 05:10, schrieb Michael Niedermayer:
> > On Sun, Mar 23, 2014 at 10:09:41PM +0100, Thilo Borgmann wrote:
> >> Am 21.03.14 20:16, schrieb Michael Niedermayer:
> >>> On Fri, Mar 21, 2014 at 05:29:16PM +0100, Thilo Borgmann wrote:
> >>>> Am 21.03.14 15:30, schrieb Michael Niedermayer:
> >>>>> On Thu, Mar 20, 2014 at 11:12:27PM +0100, Thilo Borgmann wrote:
> >>>>>> Am 04.03.14 17:16, schrieb gregory.wolfe at kodakalaris.com:
> >>>>>>> This is the second of two changes I've made as part of our upgrade to
> >>>>>>> the latest FFmpeg development branch.
> >>>>>>>
> >>>>>>> This patch enhances two aspects of metadata retrieval from AVI files.
> >>>>>>> I've attached before/after command line output from ffmpeg for each
> >>>>>>> modification. Test video files that can be used to generate the
> >>>>>>> before/after output have been uploaded to the FFmpeg FTP server.
> >>>>>>>
> >>>>>>>
> >>>>>>> Patched file: libavformat/avidec.c
> >>>>>>> Description (from commit message):
> >>>>>>>
> >>>>>>> Added function avi_extract_stream_metadata(). Some cameras (e.g., Fuji)
> >>>>>>> store stream metadata following the "strd" stream data tag. Currently,
> >>>>>>> avi_read_header() calls ff_get_extradata() to read and save this data in
> >>>>>>> the codec's "extradata" slot. This new function extracts metadata from
> >>>>>>> "extradata" by first looking for the AVIF tag, then extracting metadata
> >>>>>>> from the EXIF tags which follow it.
> >>>>>>
> >>>>>> I've rewritten almost everything to use existing EXIF functions.
> >>>>>>
> >>>>>> Patch attached, but there are 2 issues I need advise for:
> >>>>>>
> >>>>>> a) Current EXIF is in lavc only and relies on lavc/tiff.h and lavc/bytestream,
> >>>>>> so these have to be moved (to lavu)?
> >>>>>
> >>>>> using just a header with macros/inline functions is fine
> >>>>> using ff_* functions from other libs is not as ff_ is not exported
> >>>>> using avpriv_* functions in lavf from lavc is ok but the ABI/API
> >>>>> of such functions is then part of the libavcodec ABI/API, non public
> >>>>> but still, so care has to be taken with future changes to these
> >>>>> functions so their ABI/API isnt broken
> >>>>
> >>>> Ok these are the rules, but what should I do since there are ff_* functions
> >>>> used? My guess was to move to libavu because metadata decoding seems to be
> >>>> needed by formats and codecs, but I don't know if there is a better solution? Or
> >>>> make exif tag decoding a public av_* funtion in lavc?
> >>>
> >>> i suggest to rename the functions to avpriv_*
> >>> and make sure their ABI/API is future proof
> >>
> >> Updated patch(es) attached.
> >>
> >> -Thilo
> >
> >> exif.c | 4 ++--
> >> exif.h | 2 +-
> >> mjpegdec.c | 2 +-
> >> webp.c | 2 +-
> >> 4 files changed, 5 insertions(+), 5 deletions(-)
> >> 5e78f749233830fb655a5fe154eef1bc9f95decc 0001-lavc-exif-Make-EXIF-IFD-decoding-part-of-private-API.patch
> >> From 2b78e02ffbd1d36ea396d0c168c2bc17c2f44262 Mon Sep 17 00:00:00 2001
> >> From: Thilo Borgmann <thilo.borgmann at mail.de>
> >> Date: Sun, 23 Mar 2014 22:06:22 +0100
> >> Subject: [PATCH 1/3] lavc/exif: Make EXIF IFD decoding part of private
> >> API/ABI.
> >>
> >> ---
> >> libavcodec/exif.c | 4 ++--
> >> libavcodec/exif.h | 2 +-
> >> libavcodec/mjpegdec.c | 2 +-
> >> libavcodec/webp.c | 2 +-
> >> 4 files changed, 5 insertions(+), 5 deletions(-)
> >
> > needs a minor version bump
> >
> >
> > [...]
> >> @@ -822,6 +862,7 @@ static int avi_read_header(AVFormatContext *s)
> >> size = FFMIN(size, list_end - cur_pos);
> >> st = s->streams[stream_index];
> >>
> >> + if (st) {
> >
> > why is this if() needed ?
>
> I just moved it here from the extract_metadata function of Gregory's patch.
> If "st = s->streams[stream_index];" is safe, it can be avoided.
>
> Updated patches attached.
[...]
> diff --git a/libavcodec/exif.h b/libavcodec/exif.h
> index 71fe829..e673dc0 100644
> --- a/libavcodec/exif.h
> +++ b/libavcodec/exif.h
> @@ -164,7 +164,7 @@ static const struct exif_tag tag_list[] = { // JEITA CP-3451 EXIF specification:
>
> /** Recursively decodes all IFD's and
> * adds included TAGS into the metadata dictionary. */
> -int ff_exif_decode_ifd(AVCodecContext *avctx, GetByteContext *gbytes, int le,
> +int avpriv_exif_decode_ifd(AVCodecContext *avctx, GetByteContext *gbytes, int le,
> int depth, AVDictionary **metadata);
>
> #endif /* AVCODEC_EXIF_H */
> diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
> index 2fd371a..4a7811a 100644
> --- a/libavcodec/mjpegdec.c
> +++ b/libavcodec/mjpegdec.c
> @@ -1630,7 +1630,7 @@ static int mjpeg_decode_app(MJpegDecodeContext *s)
>
> // read 0th IFD and store the metadata
> // (return values > 0 indicate the presence of subimage metadata)
> - ret = ff_exif_decode_ifd(s->avctx, &gbytes, le, 0, &s->exif_metadata);
> + ret = avpriv_exif_decode_ifd(s->avctx, &gbytes, le, 0, &s->exif_metadata);
> if (ret < 0) {
> av_log(s->avctx, AV_LOG_ERROR, "mjpeg: error decoding EXIF data\n");
> return ret;
> diff --git a/libavcodec/version.h b/libavcodec/version.h
> index 381e471..f124c7b 100644
> --- a/libavcodec/version.h
> +++ b/libavcodec/version.h
> @@ -29,7 +29,7 @@
> #include "libavutil/version.h"
>
> #define LIBAVCODEC_VERSION_MAJOR 55
> -#define LIBAVCODEC_VERSION_MINOR 52
> +#define LIBAVCODEC_VERSION_MINOR 53
> #define LIBAVCODEC_VERSION_MICRO 102
micro should be reset to 100 if minor is bumped
looks good otherwise
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
It is what and why we do it that matters, not just one of them.
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