如何获取和修改 Android 上支持的音频文件的元数据？
How to get&modify metadata to supported audio files on Android?
背景
Android支持various audio files编解码。
我使用 android.media.MediaRecorder class 将音频录制到音频文件中，但我也希望显示有关我录制的文件的信息（不是标准数据，但仍然只是文本，甚至可能由用户配置），我认为最好将此信息存储在文件中。
可能要存储的数据示例：记录时间、记录位置、用户注释...
问题
MediaRecorder class 没有任何我能找到的添加甚至读取录制音频文件元数据的功能。
我也找不到类似的 class。
我试过的
我尝试搜索如何针对特定文件类型执行此操作，还尝试找到一个可以执行此操作的库。
我什至没有找到关于此信息的线索。
我为 MediaRecorder class 找到的唯一东西是一个名为“setLocation”的函数，它用于指示录制开始的位置（地理上），并查看其代码，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);
}
但是 setParameter 是私有的，我不确定是否可以将我想要的任何东西放入其中，即使我有办法访问它（例如反射）：
private native void setParameter(String nameValuePair);
我也不明白，给定一个 audio/video 文件，如何 get/modify 这种信息。例如，它不适用于 SimpleExoPlayer。
问题
如何读取、写入和修改 Android 支持的音频文件中的元数据？
这些动作有没有limitations/restrictions？
哪些文件格式适用于此？
是否可以在录制音频时添加元数据？
是否可以通过 MediaStore 实现？但是我该怎么做这些操作呢？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 (, repo here, based on here) , and it seems to work well. However, it doesn't work on latest version of the library that it uses (org.mp4parser.isoparser:1.9.37 dependency of mp4parser)，所以我将这个问题留待回答：为什么它不适用于该库的最新版本？
代码：
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
}
}
似乎无法对 Android 中所有支持的音频格式统一执行此操作。不过，特定格式的选项有限，所以我建议坚持使用一种格式。
MP3是最流行的，应该有很多选项，比如this one。
如果不想处理encoding/decoding，还有some options for a WAV format.
还有一种方法可以将元数据轨道添加到 MP4 容器 using MediaMuxer (you can have an audio-only MP4 file) or like this。
关于 MediaStore：here's an example（在第 318 页的末尾）关于如何在使用 MediaRecorder 后向其添加元数据。虽然据我所知数据不会记录在文件中。
更新
我编译了an example app using this MP4 parser library and MediaRecorder example from SDK docs。它录制音频，将其放入 MP4 容器并添加如下字符串元数据：
MetaDataInsert cmd = new MetaDataInsert();
cmd.writeRandomMetadata(fileName, "lore ipsum tralalala");
然后在下次应用启动时读取并显示此元数据：
MetaDataRead cmd = new MetaDataRead();
String text = cmd.read(fileName);
tv.setText(text);
更新#2
关于 m4a 文件扩展名：m4a is just an alias for an mp4 file with AAC audio and has the same file format。因此，您可以使用我上面的示例应用程序，只需将文件名从 audiorecordtest.mp4 更改为 audiorecordtest.m4a，并将音频编码器从 MediaRecorder.AudioEncoder.AMR_NB 更改为 MediaRecorder.AudioEncoder.AAC。
背景
Android支持various audio files编解码。
我使用 android.media.MediaRecorder class 将音频录制到音频文件中，但我也希望显示有关我录制的文件的信息（不是标准数据，但仍然只是文本，甚至可能由用户配置），我认为最好将此信息存储在文件中。
可能要存储的数据示例：记录时间、记录位置、用户注释...
问题
MediaRecorder class 没有任何我能找到的添加甚至读取录制音频文件元数据的功能。
我也找不到类似的 class。
我试过的
我尝试搜索如何针对特定文件类型执行此操作，还尝试找到一个可以执行此操作的库。
我什至没有找到关于此信息的线索。
我为 MediaRecorder class 找到的唯一东西是一个名为“setLocation”的函数，它用于指示录制开始的位置（地理上），并查看其代码，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);
}
但是 setParameter 是私有的，我不确定是否可以将我想要的任何东西放入其中，即使我有办法访问它（例如反射）：
private native void setParameter(String nameValuePair);
我也不明白，给定一个 audio/video 文件，如何 get/modify 这种信息。例如，它不适用于 SimpleExoPlayer。
问题
如何读取、写入和修改 Android 支持的音频文件中的元数据？
这些动作有没有limitations/restrictions？
哪些文件格式适用于此？
是否可以在录制音频时添加元数据？
是否可以通过 MediaStore 实现？但是我该怎么做这些操作呢？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 (org.mp4parser.isoparser:1.9.37 dependency of mp4parser)，所以我将这个问题留待回答：为什么它不适用于该库的最新版本？
代码：
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
}
}
似乎无法对 Android 中所有支持的音频格式统一执行此操作。不过，特定格式的选项有限，所以我建议坚持使用一种格式。
MP3是最流行的，应该有很多选项，比如this one。
如果不想处理encoding/decoding，还有some options for a WAV format.
还有一种方法可以将元数据轨道添加到 MP4 容器 using MediaMuxer (you can have an audio-only MP4 file) or like this。
关于 MediaStore：here's an example（在第 318 页的末尾）关于如何在使用 MediaRecorder 后向其添加元数据。虽然据我所知数据不会记录在文件中。
更新
我编译了an example app using this MP4 parser library and MediaRecorder example from SDK docs。它录制音频，将其放入 MP4 容器并添加如下字符串元数据：
MetaDataInsert cmd = new MetaDataInsert();
cmd.writeRandomMetadata(fileName, "lore ipsum tralalala");
然后在下次应用启动时读取并显示此元数据：
MetaDataRead cmd = new MetaDataRead();
String text = cmd.read(fileName);
tv.setText(text);
更新#2
关于 m4a 文件扩展名：m4a is just an alias for an mp4 file with AAC audio and has the same file format。因此，您可以使用我上面的示例应用程序，只需将文件名从 audiorecordtest.mp4 更改为 audiorecordtest.m4a，并将音频编码器从 MediaRecorder.AudioEncoder.AMR_NB 更改为 MediaRecorder.AudioEncoder.AAC。