FFMpeg:将图像与音频合并特定的持续时间 [英] FFMpeg: merge images with audio for specific duration

问题描述

过去7天，我一直在研究 FFMpeg .我需要在以下位置创建视频:

I have been working on FFMpeg from past 7 days. I am required to create a video where I need to perform following:

1. Concat 几张图像转换成从android存储设备中选取的视频.
2. 添加音乐文件(与从Android存储设备中选取的文件相同).
3. 设置每个图像的持续时间，以在视频中显示.例如如果选择了3张图像，则视频的总时长应为用户选择的3 *持续时间.

1. Concat few images into video picked from android storage.
2. Add a music file [same picked from android storage].
3. Set Duration per image to be shown in the video. e.g. if 3 images are picked then total duration of video should be 3*duration choosen by user.

我到目前为止所做的事情.

我正在为 FFmpeg 预构建二进制文件使用 implementation'nl.bravobit:android-ffmpeg:1.1.5'.以下是用于串联图像并设置持续时间的命令:

I am using implementation 'nl.bravobit:android-ffmpeg:1.1.5' for the FFmpeg prebuild binaries. Following is the command that has been used to concatenation the images and set the duration:

ffmpeg -r 1/duration_selected_by_user -f concat -safe 0 -i path_of_concat_file.txt -c:v libx264 -profile:v high -crf 20 -pix_fmt yuv420p path_of_output_video_file.mp4 

注意:

1. 通过添加用户选择的持续时间作为帧速率，我可以设置要显示的每个图像的持续时间.
2. Concat效果很好，并且视频已合并到图像中.

问题:当我尝试在同一过程中添加音频时，通过使用以下命令，即使对于较小的音频，进度也会运行很长时间:

Problem: When I try to add audio in the same process, progress run for a long time even for small audio by using the following command:

ffmpeg -r 1/duration_selected_by_user -i path_of_audio_file.mp3 -f concat -safe 0 -i path_of_concat_file.txt -c:v libx264 -profile:v high -crf 20 -pix_fmt yuv420p path_of_output_video_file.mp4

由于我对该技术不太熟悉和经验丰富，因此似乎在命令中存在一些问题.如何提高图像和音频合并的性能以获得更好的结果?

It looks like there is some issue in command as I am not much familiar and experienced with the technology. How can I improve the performance of merging images and audio to get the better results?

与上下文相关的重要链接:

https://github.com/bravobit/FFmpeg-Android

推荐答案

如评论中提到的@HB:

As @HB mentioned in the comments:

尝试在-pix_fmt yuv420p之后添加-preset ultrafast

Try adding -preset ultrafast after -pix_fmt yuv420p

预设是选项的集合，这些选项将提供一定的编码速度与压缩率.较慢的预设将提供更好的压缩(压缩是每个文件大小的质量).这意味着，例如，如果您以某个文件大小或恒定比特率为目标，则使用较慢的预设可获得更好的质量.同样，对于恒定质量的编码，只需选择较慢的预设即可简单地节省比特率.可用的速度降序预设为:

A preset is a collection of options that will provide a certain encoding speed to compression ratio. A slower preset will provide better compression (compression is quality per filesize). This means that, for example, if you target a certain file size or constant bit rate, you will achieve better quality with a slower preset. Similarly, for constant quality encoding, you will simply save bitrate by choosing a slower preset. The available presets in descending order of speed are:

• 超快
• 超快
• 非常快
• 更快
• 快速
• 中-默认预设
• 慢
• 较慢
• 非常慢
• 安慰剂–忽略它，因为它没有用

参考: https://trac.ffmpeg.org/wiki/Encode/H.264#Preset

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