如何使MATLAB中调用FFmpeg的视频剪辑功能实现亚秒级精度？

Great question! The limitation in your current code comes from using integer-only time values in the FFmpeg command. FFmpeg natively supports decimal-based time specifications (down to milliseconds or even microseconds), so we just need to adjust your MATLAB code to pass these finer-grained values. Here are two straightforward approaches:

Approach 1: Use HH:MM:SS.sss Time Format #

This keeps your existing hour/minute/second parameter structure but adds support for decimal values in the seconds component:

1. Update your command template to accept decimal seconds (we'll use 3 decimal places for millisecond precision):

% FFmpeg command template with sub-second support for start time and duration
snip = 'ffmpeg -i %s -ss %02d:%02d:%06.3f -t %02d:%02d:%06.3f -async 1 -strict -2 %s';

The %06.3f format ensures the seconds value is formatted as XX.XXX (e.g., 12.5 becomes 12.500), which FFmpeg recognizes perfectly.

2. Pass decimal values for your StartSEC and DurSEC parameters (e.g., StartSEC = 15.75 for 15 seconds and 750 milliseconds):

% Example parameters with sub-second precision
UncutFile = 'input_video.mp4';
StartHRS = 0;
StartMIN = 1;
StartSEC = 15.75; % 1 minute, 15.75 seconds
DurHRS = 0;
DurMIN = 0;
DurSEC = 3.2; % 3.2 second duration
CutFile = 'output_trimmed.mp4';

% Generate and run the command
snipstr = sprintf(snip, UncutFile, StartHRS, StartMIN, StartSEC, DurHRS, DurMIN, DurSEC, CutFile);
runsnip = system(snipstr);

Approach 2: Use Total Decimal Seconds (Simpler) #

If you prefer a more streamlined approach, calculate the total start time and duration as decimal values (total seconds with fractions), then pass those directly to FFmpeg:

% Calculate total start time and duration in seconds (with decimals)
totalStartTime = StartHRS*3600 + StartMIN*60 + StartSEC; % e.g., 75.75 seconds
totalDuration = DurHRS*3600 + DurMIN*60 + DurSEC; % e.g., 3.2 seconds

% Simplified FFmpeg command template
snip = 'ffmpeg -i %s -ss %.3f -t %.3f -async 1 -strict -2 %s';

% Generate and run the command
snipstr = sprintf(snip, UncutFile, totalStartTime, totalDuration, CutFile);
runsnip = system(snipstr);

Key Note for Maximum Precision #

If you want true sub-second accuracy, avoid adding the -c:v copy flag to your FFmpeg command. That flag tells FFmpeg to copy video streams directly, which limits trimming to the nearest keyframe (often several seconds apart). Without it, FFmpeg will re-encode the video, allowing you to trim to exactly the time you specify—even down to individual frames or fractions of a frame.

内容的提问来源于stack exchange，提问作者Micah T