Author Topic: about video merge & cut  (Read 452 times)

kkk

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about video merge & cut
« on: August 24, 2018, 02:18:46 PM »
hello
I know little English,can i ask question in Chinese?
整个论坛看了十几页,没看到解决办法,又没法用中文搜索,劳烦作者看下这问题怎么解决,谢谢
1、第一个是视频合并的问题
用一张图片制作了一个10s的视频,里面没有声音。然后把这个视频跟另一个有声音的视频进行合并,再输出。结果是输出的视频都没有声音了,正常应该是在前10s是无声音的,之后的要有声音才对。这问题有办法解决?
win7系统,2.7.1的版本

2、另一个问题是关于无损剪切视频
对视频进行剪切,开头位置是要在关键帧I帧上面,剪切后输出才能正常播放,如果是在P/B帧上面,那么输出的视频在开头位置就会花屏、卡屏或者绿屏。这个出现问题的原因我懂,但是有办法解决吗。因为剪切的位置,前一个I帧跟后一个I帧画面变化非常大,中间有5s的时间,从中间剪切后,编码如果选的是直接copy的,输出之后,文件开头就会卡屏,如果是重新进行编码,又担心会影响分辨率,而且编码要花很长时间。
有看到一个说是能解决这种问题的,大概意思是,剪切之后,在第一个I帧之前的内容重新编码,而I帧之后所有的内容都是copy原视频的内容,类似于这个软件以前有提到的smart copy方案,可惜这个软件说是只支持一种格式而已。
这种方式就是可以让导出时既省时间,又能很好的保存原视频的清晰度。这软件能让普通的视频,比如flv avi mkv之类的进行这样的剪切吗
http://tieba.baidu.com/p/5844942077?pid=121519872927&cid=0#121519872927






eumagga0x2a

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Re: about video merge & cut
« Reply #1 on: August 24, 2018, 03:16:34 PM »
I have to rely on Google Translate, so I apologize in advance for possible misunderstandings.

1. The number of soundtracks, their audio codec parameters and the channel layout off all appended source videos must strictly match. You could extract the soundtrack of the second video, prepend silence for the duration of the first video using a wave editor (e.g. Audacity), export the audio as 16 bit low-endian PCM (.wav) or MP3 and add it as an external soundtrack in Avidemux.

2. The feature of legacy Avidemux versions to re-encode only portions of video was incompatible with modern video codecs like H.264 and HEVC and therefore removed a long time ago. If you need to cut at other positions as at I-frames (more precisely, at IDR frames = instant decoder refresh frames), you must re-encode the entire video.

kkk

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Re: about video merge & cut
« Reply #2 on: August 25, 2018, 04:33:06 AM »
ok,I see,thank you
maybe the second question is too hard  to solve at present
I ask many people for the ‘smart copy’ in my country,no one have any solution
anyhow,thanks for your answer