Le 04/06/2023 à 20:24, Tomas Härdin a écrit :
tor 2023-06-01 klockan 17:19 +0200 skrev Cédric Le Barz:
Attach to this mail, is my new patch for adding jpeg2000 sub-
descriptor
in MXF file taking into account remarks from FFmpeg community
(remarks
from Pierre-Anthony above as well as this from Tomas), i.e. :
1 - When there is a mismatch in components number, this is now
process
as an error.
2 - When defining and using the J2K descriptor items, I now refer to
the
symbol name from the SMPTE registers (X0siz, XT0siz...)
3 - As suggested, I make use of jpeg2000_read_main_headers() in
libavcodec. But, I let the parsing function in mxfenc.c file as all
other parsing functions are in this file (mxf_parse_mpeg2_frame,
mxf_parse_h264_frame...). The use of jpeg2000_read_main_headers() in
mxfenc implies some minor modifications in jpeg2000 files :
* rename of Jpeg2000Tile structure to J2kTile in j2kenc.c (to avoid
redefinition)
* move some structure declarations from jpeg2000dec.c to jpeg2000.h
* make jpeg2000_read_main_headers() function "public"
For this you need to prefix the name with ff_ and bump libavcodec's
minor version number
+static int mxf_parse_jpeg2000_frame(AVFormatContext *s, AVStream
*st, AVPacket *pkt)
+{
+ MXFContext *mxf = s->priv_data;
+ MXFStreamContext *sc = st->priv_data;
+ int component_count = av_pix_fmt_count_planes(st->codecpar-
format);
+ Jpeg2000DecoderContext jpeg2000ctx;
This makes sizeof(Jpeg2000DecoderContext) part of the public API which
is a big no-no. Consider making the fields part of a different smaller
struct instead that is also included in Jpeg2000DecoderContext. The
safest option is to have a function that allocates that struct. The
reason for this is because we might want to read other things from the
headers at a later date. Another possibility is to pass a bunch of
pointers to ints that the parsed values get written to. If at a later
date we need to parse more fields then we can introduce
ff_jpeg2000_read_main_headers_2() and so on. The latter seems easier
API stability wise, if a bit tedious with the number of function
arguments.
/Tomas
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
Hi,
I'm facing a problem to get the jpeg2000 information I need to build the
mxf file.
All the functions to extract jpeg2000 information exist : they are
located in libavcodec side and used Jpeg2000DecoderContext, which is not
obviously public and therefore unknown from libavformat side.
Is there a way to get a pointer on the Jpeg2000DecoderContext (at least
a void*) from libavcodec side ?
Thanks for your help.
Cédric
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
