[Libav-user] MJPEG Quantization tables

[Виктор Мулин]

Thanks for the answer.
intra_matrix and inter_matrix are of type uint16_t, and tables from
jpegtables.c are of type uint8_t. What to do? Make a cast of uint8_t * to
uint16_t * or define a new array of type uint16_t by filling it with values
from standard tables?
Will these tables be added to the output file automatically after I specify
array references in the AVCodecContext structure?

пн, 18 мая 2020 г. в 19:54, Richard Hussong <rhussong at westpond.com>:

>
>
> On Mon, May 18, 2020 at 7:38 AM Виктор Мулин <17sep96 at gmail.com> wrote:
>
>> Hello! When using the mjpeg codec to convert an image from bmp to jpg
>> format, a picture with one quantization table is created. I need two
>> standard tables described in the jpeg iso / iec 10918-1 T.81 standard in
>> Appendix K.1 and K.2 to be added to the output image file. I also found
>> them in the ffmpeg source codes (jpegtables.c -> std_luminance_quant_tbl
>> and jpegtables.c -> std_chrominance_quant_tbl [url:
>> https://ffmpeg.org/doxygen/trunk/jpegtables_8c_source.html]. I looked
>> through the mailing list archive and found old solutions (
>> https://ffmpeg.org/pipermail/libav-user/2015-July/008318.html), but now
>> the av_codec_set_chroma_intra_matrix () function is declared depricated.
>> How do I get what I want? How to set intra_matrix, chroma_intra_matrix and
>> inter_matrix (in the description they are almost the same)?
>>
>
> The intra_matrix and inter_matrix can now be set directly in the
> AVCodecContext structure. See
> https://ffmpeg.org/doxygen/trunk/structAVCodecContext.html, and search
> for "intra_matrix" and "inter_matrix".
>
> P.S .: Sorry, I don't speak English well. I use google translator.
>>
>
> Don't worry - what you wrote is clear enough.
>
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