如何使用 ffmpeg 指定恒定帧速率

发布于 2025-01-12 15:24:38 字数 618 浏览 2 评论 0原文

我有一个视频流 url，它以 1 fps 到 25 fps 的速率提供视频帧（帧速率是可变的）。我的目标是将其存储为 mp4 文件，帧速率恒定为 30fps。我还期望录制视频的持续时间与执行 ffmpeg 命令的持续时间相同。

目前我使用以下命令

ffmpeg -f mjpeg -i video_stream_url \
  -vf "pad= ceil(iw/2)*2:ceil(ih/2)*2",\
       drawtext=text='%{localtime}':fontfile=/Windows/Fonts/Arial.ttf:fontcolor=white:fontsize=25:x=(W-tw)/2:y=h-(2*lh):box=1:boxcolor=0x00000000@1 \
  -c:v copy -vcodec libx264  filename.mp4

当前观察录制的视频时长几乎是我执行命令时长的一半。为了调试问题，我在帧上添加了时间戳。当我播放录制的文件时，视频中与源流中的低 fps 相对应的视频部分以快进模式播放，而视频的其余部分（与源中的 25 fps 相对应）正常播放。

如何在整个过程中保持 30 fps 的统一帧速率，并确保录制的视频文件持续时间与我执行命令的实际持续时间相同

原文

I have a video stream url that gives video frame at the rate of 1fps to 25 fps (frame rate is variable). My aim is to store this as an mp4 file with a constant frame rate of 30fps. I'm also expecting that the duration of the recorded video to be same as the duration for which I execute the ffmpeg command.

At present I use the following command

ffmpeg -f mjpeg -i video_stream_url \
  -vf "pad= ceil(iw/2)*2:ceil(ih/2)*2",\
       drawtext=text='%{localtime}':fontfile=/Windows/Fonts/Arial.ttf:fontcolor=white:fontsize=25:x=(W-tw)/2:y=h-(2*lh):box=1:boxcolor=0x00000000@1 \
  -c:v copy -vcodec libx264  filename.mp4

Present observation
The recorded video duration is almost half of the duration for which I had executed the command. To debug the problem, I have added the timestamp on the frames. When I play the recorded file, the video part of video which corresponds to low fps at source stream plays in a fast forward mode and the rest of the video (corresponding to 25 fps at source) plays normally.

How can I maintain a uniform frame rate of 30 fps throughout and ensure that recorded video file duration is same as the actual duration for which I had executed the command

分享到QQ

分享到微博