New submission from Dan <[email protected]>:
I am using libavformat/libavcodec to decode a mjpeg stream.
The problem that I encountered was that the ends of my jpeg images were
not being detected, and thus av_read_frame wasn't returning.
It seems that in mjpeg_parser.c, the function 'find_frame_end' has a
single condition for detecting the end of a jpeg: EOF.
Since I'm feeding in a stream, I never hit an EOF, and therefore it
always returned END_NOT_FOUND.
To fix this, I added another condition: the presence of the 'EOI' flag
(0xFFD9).
...
if(state == 0xFFD9){
return i+1;
}
else if(state == 0xFFD8){
pc->frame_start_found=0;
pc->state=0;
return i-1;
}
...
The EOI flag is in the JPEG standard:
http://gvsoft.homedns.org/exif/exif-explanation.html
The function is detecting 0xFFD8 as the SOI (start of image), but for
some reason, not 0xFFD9 as the EOI.
----------
messages: 13282
priority: normal
status: new
substatus: new
title: mjpeg_parser does not detect end of jpeg in jpeg stream (easy fix)
topic: avcodec
type: bug
________________________________________________
FFmpeg issue tracker <[email protected]>
<https://roundup.ffmpeg.org/issue2507>
________________________________________________
