vfx.TimeSymmetrize cutoffs 1 second at the end and makes picture jump

[AndrewFucher]

Hi,
While trying to use vfx.TimeSymmetrize I found out that it cutoffs 1 second at the end (start for backward part)

Issue lies in how slices are calculated in Clip class.

Expected Behavior

TimeSymmetrize Will add exactly same video but in reverse

Actual Behavior

Reversed part is cut by 1 second

Steps to Reproduce the Problem

Just use this effect TimeSymmetrize

Specifications

• Python Version: 3.13
• MoviePy Version: 2.1.1
• Platform Name: Windows
• Platform Version: 11

[chenhaoch]

I encountered the same issue. Did you find a solution?
I tried TimeMirror and TimeSymmetrize. Both have this issue.

[OsaAjani]

Hi, that's the next one on my list, I'll take a look when I can !

[OsaAjani]

Hi, @chenhaoch and @AndrewFucher could any of you provide some code example triggering the bug, including the media used in the code example.
Did you use subclipped before symmetrize ?

[chenhaoch]

I didn't use subclipped 。

my code:

    video_files = [os.path.join('videos', f) for f in os.listdir('videos') if f.endswith('.mp4')]
    video_clips = [VideoFileClip(f) for f in video_files]
    
    # 创建正序和逆序视频片段
    processed_clips = []
    for clip in video_clips:
        processed_clips.append(clip)
        mirrored_clip = clip[::-1]
        # processed_clips.append(clip.with_effects([vfx.TimeSymmetrize()]))
        processed_clips.append(mirrored_clip)
        # mirrored_clip.write_videofile('output.mp4', codec='libx264', audio_codec='aac', audio_bitrate='192k')
    
    # 合并视频
    final_video = concatenate_videoclips(processed_clips)
    final_video.write_videofile('video_output.mp4', codec='libx264', audio_codec='aac', audio_bitrate='192k')

[chenhaoch]

and I checked the first and last frames, they don't correspond.
mirrored_first_0.jpg and original_last_0.jpg are different.

processed_clips = []
    for i, new_clip in enumerate(video_clips):
        # clip = new_clip.subclipped(0,5)
        # 保存原始视频第一帧和最后一帧
        frame = clip.get_frame(0)
        img = Image.fromarray(frame)
        img.save(f'frames/original_first_{i}.jpg')
        
        # 使用iter_frames获取原始视频最后一帧
        clip_frames = list(clip.iter_frames())
        clip_last_frame = clip_frames[-1]
        img = Image.fromarray(clip_last_frame)
        img.save(f'frames/original_last_{i}.jpg')
        
        processed_clips.append(clip)
        
        # 保存TimeMirror处理后的第一帧和最后一帧
        mirrored_clip = clip.with_effects([vfx.TimeMirror()])
        frame = mirrored_clip.get_frame(0)
        img = Image.fromarray(frame)
        img.save(f'frames/mirrored_first_{i}.jpg')
        
        # 使用iter_frames获取TimeMirror处理后的最后一帧
        mirrored_clip_frames = list(mirrored_clip.iter_frames())
        mirrored_clip_last_frame = mirrored_clip_frames[-1]
        img = Image.fromarray(mirrored_clip_last_frame)
        img.save(f'frames/mirrored_last_{i}.jpg')
        
        processed_clips.append(mirrored_clip)

[OsaAjani]

Hi, I think I found the problem, but another matter seems to appear when applying some sub clipping, so I will need a bit of time to fix both.