issue to fix the offset

[EhsanRusta]

I'm trying to remove the offset of a video, the offset is -15 and use the following command to shift the video,
" ffmpeg -y -i temp.mp4 -itsoffset -0.5 -i newtemp.mp4 -ss -0.5 -t 9.2 -map 0:v -map 1:a new0.mp4 "
but new video has offset equal to 8! I don't know waht is the issue, should I change anything else?
the FPS has changed to 25

[ashok-arjun]

@EhsanRusta What's the FPS of the original video? You should specify -itsoffset OFFSET/FPS where FPS is the original video's FPS I guess

[devsvarun]

@EhsanRusta What's the FPS of the original video? You should specify -itsoffset OFFSET/FPS where FPS is the original video's FPS I guess

still the offset of the corrected video is not close to 1

[WudiJoey]

First, you should get the original FPS for each video. And then, synchronize video according to its AV OFFSET:

1. when av offset is positive:
   ffmpeg -i input.mp4 -itsoffset abs(OFFSET)/FPS -i input.mp4 -map 0:v -map 1:a -c copy output.mp4

2. when av offset is negative:
   ffmpeg -i input.mp4 -itsoffset abs(OFFSET)/FPS -i input.mp4 -map 1:v -map 0:a -c copy -t video_len-abs(OFFSET)/FPS output.mp4

After doing this, OFFSET for the new video will be 0. But i only test on few videos.

Referring to https://superuser.com/a/983153

[tailangjun]

2. -t video_len-abs(OFFSET)/FPS

Why aren’t they all video_len-abs(OFFSET)/FPS?

[WudiJoey]

您好，您的来信我已经收到，会尽快回复。  

[tailangjun]

您好，您的来信我已经收到，会尽快回复。

多谢兄弟，我是想问为啥一个时长不变，一个变成 video_len-abs(OFFSET)/FPS了

[WudiJoey]

您好，您的来信我已经收到，会尽快回复。

多谢兄弟，我是想问为啥一个时长不变，一个变成 video_len-abs(OFFSET)/FPS了

嗷这里是考虑到音频提前之后视频会有一部分没有声音就裁掉了，我想了一下实际上应该同时对校正后视频的头尾进行裁剪，如果你的offset是几秒的话得到的视频前几秒是【卡顿有声音】或者【画面在动但是无声音】
但是当你的offset就几帧的前提下没有太大影响，offset超过几秒的话有时候那个视频本身就对不上音频和唇形

[prometheus-alien]

First, you should get the original FPS for each video. And then, synchronize video according to its AV OFFSET:

1. when av offset is positive:
   ffmpeg -i input.mp4 -itsoffset abs(OFFSET)/FPS -i input.mp4 -map 0:v -map 1:a -c copy output.mp4
2. when av offset is negative:
   ffmpeg -i input.mp4 -itsoffset abs(OFFSET)/FPS -i input.mp4 -map 1:v -map 0:a -c copy -t video_len-abs(OFFSET)/FPS output.mp4

After doing this, OFFSET for the new video will be 0. But i only test on few videos.

Referring to https://superuser.com/a/983153

谢谢，好人一生平安

[prometheus-alien]

您好，您的来信我已经收到，会尽快回复。

多谢兄弟，我是想问为啥一个时长不变，一个变成 video_len-abs(OFFSET)/FPS了

嗷这里是考虑到音频提前之后视频会有一部分没有声音就裁掉了，我想了一下实际上应该同时对校正后视频的头尾进行裁剪，如果你的offset是几秒的话得到的视频前几秒是【卡顿有声音】或者【画面在动但是无声音】 但是当你的offset就几帧的前提下没有太大影响，offset超过几秒的话有时候那个视频本身就对不上音频和唇形

谢谢子华兄