第一步，解析视频文件

private static String processVideo(String filePath) {List<String> commend=new java.util.ArrayList<String>();commend.add("ffmpeg");//可以设置环境变量从而省去这行//d:\ffmpeg\ffmpeg.execommend.add("-i");commend.add(filePath);try {ProcessBuilder builder = new ProcessBuilder();builder.command(commend);builder.redirectErrorStream(true);Process p= builder.start();BufferedReader buf = null; // 保存ffmpeg的输出结果流String line = null;buf = new BufferedReader(new InputStreamReader(p.getInputStream()));StringBuffer sb= new StringBuffer();while ((line = buf.readLine()) != null) {sb.append(line);continue;}p.waitFor();//这里线程阻塞，将等待外部转换进程运行成功运行结束后，才往下执行return sb.toString();} catch (Exception e) {System.out.println("ffmpeg解析视频文件【" + filePath +"】失败!");return null;}}

第二步，获取相关metadata，获取视频的旋转角度

private static String getRotate() {String rotate = "";String result =   processVideo(videoPath);System.out.println(result);if(StringUtils.isNotEmpty(result)){PatternCompiler compiler =new Perl5Compiler();try {String regexRotate ="rotate\\s*:\\s*(\\w*)\\s*";Pattern patternRotate = compiler.compile(regexRotate, Perl5Compiler.CASE_INSENSITIVE_MASK);PatternMatcher matcherRotate = new Perl5Matcher();if(matcherRotate.contains(result, patternRotate)){MatchResult re = matcherRotate.getMatch();rotate = re.group(1);System.out.println("rotate:"+rotate);}} catch (MalformedPatternException e) {System.out.println("获取【" + videoPath +"】视频信息失败!");}System.out.println("获取【" + videoPath +"】视频信息成功!");}else{System.out.println("执行成功！但未获取到【" + videoPath +"】视频信息!");}return rotate;}

第三步，根据rotate角度信息，调用旋转命令

 private static boolean rotate90mp4(String rotate) {List<String> commend = new ArrayList<String>();//ffmpeg -i demo.mp4 -vf "transpose=1" o.mp4try {Runtime runtime = Runtime.getRuntime();
// String cmd = " ffmpeg -i "+ videoPath + " -vf \"transpose=1\"  d:\\out\\vertical.mp4";StringBuffer buf = new StringBuffer();buf.append(" ffmpeg ");buf.append(" -i ");buf.append(videoPath);if(!StringUtils.isBlank(rotate)){buf.append(" -vf ");if(rotate.equals("90"))buf.append(" \"transpose=1\" ");else if(rotate.equals("180"))buf.append(" \"transpose=2,transpose=2\" ");else if(rotate.equals("270"))buf.append(" \"transpose=2\" ");}buf.append(destPath);runtime.exec(buf.toString());return true;} catch (Exception e) {e.printStackTrace();return false;}}