我服了，使用 Java 和 Python 运行 ffmpeg 命令， Java 运行了大半天不出结果， Python 秒出
qwertty01 · 2020-10-18 11:27:49 +08:00 · 2200 次点击这是一个创建于 1508 天前的主题，其中的信息可能已经有所发展或是发生改变。
大佬们，能不能说一下为什么这样啊 java
public class TestApp {
public static void main(String[] args) throws IOException, InterruptedException {
ProcessBuilder processBuilder = new ProcessBuilder("D:\\ffmpeg\\bin\\ffmpeg.exe", "-i", "D:\\test\\test.mp4",
"-strict", "-2", "-vf", "crop=280:360:0:0", "D:\\test\\out.mp4"
);
Process process = processBuilder.start();
process.waitFor();
}
}
python
os.system("D:\\ffmpeg\\bin\\ffmpeg.exe -i D:\\test\\test.mp4 -strict -2 -vf crop=280:360:0:0 D:\\test\\out.mp4")
第 1 条附言 · 2020-10-18 15:14:30 +08:00
问题解决了, 设置 redirectErrorStream(true)，然后再从 inputstream 不断读就行了
```
package priv.sunmd.app
import java.io.BufferedReader
import java.io.IOException
import java.io.InputStream
import java.io.InputStreamReader
object TestC {
@Throws(IOException::class, InterruptedException::class)
@JvmStatic
fun main(args: Array<String>) {
val processBuilder = ProcessBuilder(
"D:\\ffmpeg\\bin\\ffmpeg.exe", "-i", "D:\\test\\test.mp4",
"-strict", "-2", "-vf", "crop=280:360:0:0", "D:\\test\\out.mp4"
)
val process = processBuilder.redirectErrorStream(true).start()
ReadStream(process.inputStream).run()
}
}
internal class ReadStream(private val inputStream: InputStream) : Runnable {
override fun run() {
val bufferedReader = BufferedReader(
InputStreamReader(inputStream)
)
try {
var line: String?
while (bufferedReader.readLine().also { line = it } != null) {
println(line)
}
} catch (e: IOException) {
e.printStackTrace()
}
}
}
```
```
package priv.sunmd.app
import java.io.BufferedReader
import java.io.IOException
import java.io.InputStream
import java.io.InputStreamReader
object TestC {
@Throws(IOException::class, InterruptedException::class)
@JvmStatic
fun main(args: Array<String>) {
val processBuilder = ProcessBuilder(
"D:\\ffmpeg\\bin\\ffmpeg.exe", "-i", "D:\\test\\test.mp4",
"-strict", "-2", "-vf", "crop=280:360:0:0", "D:\\test\\out.mp4"
)
val process = processBuilder.redirectErrorStream(true).start()
ReadStream(process.inputStream).run()
}
}
internal class ReadStream(private val inputStream: InputStream) : Runnable {
override fun run() {
val bufferedReader = BufferedReader(
InputStreamReader(inputStream)
)
try {
var line: String?
while (bufferedReader.readLine().also { line = it } != null) {
println(line)
}
} catch (e: IOException) {
e.printStackTrace()
}
}
}
```
 |
1
xl224 2020-10-18 12:25:33 +08:00 via iPhone  1
把 stdout 和 stderr 读出来，也可以设置转发 err 到 stdout 然后一起读取出来，不读取如果写满缓冲会挂起程序，ffmpeg 我记得会有大量输出信息
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2
paulluis2dev 2020-10-18 12:49:59 +08:00 via iPhone
没用对，说明不了问题
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3
qwertty01 OP @xl224 大佬这样写行吗？
``` Process process = processBuilder.start(); byte[] bytes = new byte[104]; while (true) { if (process.getInputStream().read(bytes) != -1) { System.out.println(bytes.toString()); } else { break; } } ``` |
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4
lxk11153 2020-10-18 13:27:24 +08:00
-y (global)
Overwrite output files without asking. |
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5
chihiro2014 2020-10-18 13:29:16 +08:00
= =说起来，我服务端也是用 Java 调用 ffmpeg，完全没这种问题
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6
lxk11153 2020-10-18 13:40:29 +08:00
-strict 拿来干嘛的？
---- try(InputStream pis=process.getInputStream()){ // org.apache.commons.io.IOUtils#toString(InputStream, Charset) } |
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