背景
安卓支持各种音频文件编码和解码。
我使用将音频录制到音频文件中android.media.MediaRecorder类，但我也希望显示有关我记录的文件的信息（不是标准数据，但仍然只是文本，甚至可能由用户配置），并且我认为最好将此信息存储在文件中。
可能存储的数据示例：记录时间、记录地点、用户注释...
问题
MediaRecorder 类没有我可以找到的任何功能来添加甚至读取录制的音频文件的元数据。
我也找不到类似的课程。
我尝试过的
我尝试搜索如何针对特定文件类型执行此操作，并尝试找到一个可以执行此操作的库。
我什至没有找到有关此信息的线索。
我为 MediaRecorder 类找到的唯一东西是一个名为“设置位置" ，用于指示录音开始的位置（地理上），查看其代码，我可以看到它设置了参数：
public void setLocation(float latitude, float longitude) {
int latitudex10000 = (int) (latitude * 10000 + 0.5);
int longitudex10000 = (int) (longitude * 10000 + 0.5);
if (latitudex10000 > 900000 || latitudex10000 < -900000) {
String msg = "Latitude: " + latitude + " out of range.";
throw new IllegalArgumentException(msg);
}
if (longitudex10000 > 1800000 || longitudex10000 < -1800000) {
String msg = "Longitude: " + longitude + " out of range";
throw new IllegalArgumentException(msg);
}
setParameter("param-geotag-latitude=" + latitudex10000);
setParameter("param-geotag-longitude=" + longitudex10000);
}
But setParameter是私有的，我不确定是否可以将我想要的任何内容放入其中，即使我有办法访问它（例如反射）：
private native void setParameter(String nameValuePair);
给定音频/视频文件，我也不知道如何获取/修改此类信息。它不适用于简单Exo播放器， 例如。
问题
如何读取、写入和修改 Android 支持的音频文件中的元数据？
这些行动有任何限制/限制吗？
哪些文件格式可用于此？
录制音频时是否可以添加元数据？
是否有可能通过 MediaStore ？但那么我该如何进行这些操作呢？支持哪些文件？元数据是否保留在文件中？
编辑：好的，我已经查看了提供给我的解决方案（here, repo here， 基于here），而且看起来效果很好。但是，它不适用于它使用的最新版本的库（org.mp4parser.isoparser:1.9.37的依赖性mp4解析器），所以我留下这个问题来回答：为什么它不能在这个库的最新版本上工作？
Code:
object MediaMetaDataUtil {
interface PrepareBoxListener {
fun prepareBox(existingBox: Box?): Box
}
@WorkerThread
fun <T : Box> readMetadata(mediaFilePath: String, boxType: String): T? {
return try {
val isoFile = IsoFile(FileDataSourceImpl(FileInputStream(mediaFilePath).channel))
val nam = Path.getPath<T>(isoFile, "/moov[0]/udta[0]/meta[0]/ilst/$boxType")
isoFile.close()
nam
} catch (e: Exception) {
null
}
}
/**
* @param boxType the type of the box. Example is "©nam" (AppleNameBox.TYPE). More available here: https://kdenlive.org/en/project/adding-meta-data-to-mp4-video/
* @param listener used to prepare the existing or new box
* */
@WorkerThread
@Throws(IOException::class)
fun writeMetadata(mediaFilePath: String, boxType: String, listener: PrepareBoxListener) {
val videoFile = File(mediaFilePath)
if (!videoFile.exists()) {
throw FileNotFoundException("File $mediaFilePath not exists")
}
if (!videoFile.canWrite()) {
throw IllegalStateException("No write permissions to file $mediaFilePath")
}
val isoFile = IsoFile(mediaFilePath)
val moov = isoFile.getBoxes<MovieBox>(MovieBox::class.java)[0]
var freeBox = findFreeBox(moov)
val correctOffset = needsOffsetCorrection(isoFile)
val sizeBefore = moov.size
var offset: Long = 0
for (box in isoFile.boxes) {
if ("moov" == box.type) {
break
}
offset += box.size
}
// Create structure or just navigate to Apple List Box.
var userDataBox: UserDataBox? = Path.getPath(moov, "udta")
if (userDataBox == null) {
userDataBox = UserDataBox()
moov.addBox(userDataBox)
}
var metaBox: MetaBox? = Path.getPath(userDataBox, "meta")
if (metaBox == null) {
metaBox = MetaBox()
val hdlr = HandlerBox()
hdlr.handlerType = "mdir"
metaBox.addBox(hdlr)
userDataBox.addBox(metaBox)
}
var ilst: AppleItemListBox? = Path.getPath(metaBox, "ilst")
if (ilst == null) {
ilst = AppleItemListBox()
metaBox.addBox(ilst)
}
if (freeBox == null) {
freeBox = FreeBox(128 * 1024)
metaBox.addBox(freeBox)
}
// Got Apple List Box
var nam: Box? = Path.getPath(ilst, boxType)
nam = listener.prepareBox(nam)
ilst.addBox(nam)
var sizeAfter = moov.size
var diff = sizeAfter - sizeBefore
// This is the difference of before/after
// can we compensate by resizing a Free Box we have found?
if (freeBox.data.limit() > diff) {
// either shrink or grow!
freeBox.data = ByteBuffer.allocate((freeBox.data.limit() - diff).toInt())
sizeAfter = moov.size
diff = sizeAfter - sizeBefore
}
if (correctOffset && diff != 0L) {
correctChunkOffsets(moov, diff)
}
val baos = BetterByteArrayOutputStream()
moov.getBox(Channels.newChannel(baos))
isoFile.close()
val fc: FileChannel = if (diff != 0L) {
// this is not good: We have to insert bytes in the middle of the file
// and this costs time as it requires re-writing most of the file's data
splitFileAndInsert(videoFile, offset, sizeAfter - sizeBefore)
} else {
// simple overwrite of something with the file
RandomAccessFile(videoFile, "rw").channel
}
fc.position(offset)
fc.write(ByteBuffer.wrap(baos.buffer, 0, baos.size()))
fc.close()
}
@WorkerThread
@Throws(IOException::class)
fun splitFileAndInsert(f: File, pos: Long, length: Long): FileChannel {
val read = RandomAccessFile(f, "r").channel
val tmp = File.createTempFile("ChangeMetaData", "splitFileAndInsert")
val tmpWrite = RandomAccessFile(tmp, "rw").channel
read.position(pos)
tmpWrite.transferFrom(read, 0, read.size() - pos)
read.close()
val write = RandomAccessFile(f, "rw").channel
write.position(pos + length)
tmpWrite.position(0)
var transferred: Long = 0
while (true) {
transferred += tmpWrite.transferTo(0, tmpWrite.size() - transferred, write)
if (transferred == tmpWrite.size())
break
//System.out.println(transferred);
}
//System.out.println(transferred);
tmpWrite.close()
tmp.delete()
return write
}
@WorkerThread
private fun needsOffsetCorrection(isoFile: IsoFile): Boolean {
if (Path.getPath<Box>(isoFile, "moov[0]/mvex[0]") != null) {
// Fragmented files don't need a correction
return false
} else {
// no correction needed if mdat is before moov as insert into moov want change the offsets of mdat
for (box in isoFile.boxes) {
if ("moov" == box.type) {
return true
}
if ("mdat" == box.type) {
return false
}
}
throw RuntimeException("I need moov or mdat. Otherwise all this doesn't make sense")
}
}
@WorkerThread
private fun findFreeBox(c: Container): FreeBox? {
for (box in c.boxes) {
// System.err.println(box.type)
if (box is FreeBox)
return box
if (box is Container) {
val freeBox = findFreeBox(box as Container)
if (freeBox != null) {
return freeBox
}
}
}
return null
}
@WorkerThread
private fun correctChunkOffsets(movieBox: MovieBox, correction: Long) {
var chunkOffsetBoxes = Path.getPaths<ChunkOffsetBox>(movieBox as Box, "trak/mdia[0]/minf[0]/stbl[0]/stco[0]")
if (chunkOffsetBoxes.isEmpty())
chunkOffsetBoxes = Path.getPaths(movieBox as Box, "trak/mdia[0]/minf[0]/stbl[0]/st64[0]")
for (chunkOffsetBox in chunkOffsetBoxes) {
val cOffsets = chunkOffsetBox.chunkOffsets
for (i in cOffsets.indices)
cOffsets[i] += correction
}
}
private class BetterByteArrayOutputStream : ByteArrayOutputStream() {
val buffer: ByteArray
get() = buf
}
}
写作和阅读标题的示例用法：
object MediaMetaData {
@JvmStatic
@Throws(IOException::class)
fun writeTitle(mediaFilePath: String, title: String) {
MediaMetaDataUtil.writeMetadata(mediaFilePath, AppleNameBox.TYPE, object : MediaMetaDataUtil.PrepareBoxListener {
override fun prepareBox(existingBox: Box?): Box {
var nam: AppleNameBox? = existingBox as AppleNameBox?
if (nam == null)
nam = AppleNameBox()
nam.dataCountry = 0
nam.dataLanguage = 0
nam.value = title
return nam
}
})
}
@JvmStatic
fun readTitle(mediaFilePath: String): String? {
return MediaMetaDataUtil.readMetadata<AppleNameBox>(mediaFilePath, AppleNameBox.TYPE)?.value
}
}
