JR hahne's profile - activity

Hi All,

there is a known bug in the VideoCapture ffmpeg module. It occurs while loading videos withouta codec: http://code.opencv.org/issues/1915

I had some time now to debug this bug and found the issue in:

CvCapture_FFMPEG::grabFrame()

In the function

avcodec_decode_video2(video_st->codec, picture, &got_picture, &packet);

the AVFrame picture get set. But after

av_free_packet (&packet);

I get: "error: Cannot access memory at address..." for picture.data[0] which leads to a segmentation fault later in the function sws_scale().

I can encode this video with a video codec using ffmpeg or whatever and I get no segmentation fault (memory in picture.data[0] can still be accessed).

Of course there is an easy fix for this bug: Simply comment out / delete

av_free_packet (&packet);

This is working fine for me. Now I can process videos with and without codecs. But I am not sure if this will lead to memory issues if av_free_packet gets not called. Is there anybody who is familiar with FFmpeg and can help me here?

Thanks a lot!

Hi there,

I am testing the CascadeClassifier from OpenCV using the pre-trained files

• haarcascade_eye_tree_eyeglasses.xml
• haarcascade_frontalface_default.xml

I am using the official OpenCV builds for Windows from SourceForge and the precompiled packages on Ubuntu. I am using the same video input and the same source code for my program.

Anyway, I am getting different results on Linux compared to the results on Windows. The results differs only a few pixels but which is still significant in my case as the results of the following processing slightly differs which pretends to compare the results.

Does anybody know the reason for this or has at least any hints why this is the case? Or should this not be the case?

Thanks a lot in advance, Johannes