Bug 1671626 Comment 8 Edit History

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Original comment by

Alastor Wu [:alwu]

on 2020-11-18 17:23:21 PST

I'm still suffering from the build/link issues, here I'm going to describe the problems I encountered.

---
1. Use `MediaPlayer` framework directly (**failed**)
As we are still using 10.11 on the try server, which is an older SDK, we are not able to find `MediaPlayer` framework to link on that SDK version.

2. Declare `extern ... MPMediaItemPropertyXXX` (**failed**)
Then I tried to define something following in `MediaPlayerWrapper.h`

 ```
extern NSString* const _Nullable MPMediaItemPropertyTitle;
extern NSString* const _Nullable MPMediaItemPropertyArtist;
extern NSString* const _Nullable MPMediaItemPropertyAlbumTitle;
```
On the linking stage, it would show the error of not being able to find those symbols. Those variables are originally defined in `MPMediaItem.h`, which look like that,

```
MP_EXTERN NSString * const MPMediaItemPropertyTitle                                                                     // filterable
    MP_API(ios(3.0), tvos(9.0), watchos(5.0), macos(10.12.2));
@property (nonatomic, readonly, nullable) NSString *title MP_API(ios(7.0));

MP_EXTERN NSString * const MPMediaItemPropertyAlbumTitle
    MP_API(ios(3.0), tvos(9.0), watchos(5.0), macos(10.12.2));                                                          // filterable
@property (nonatomic, readonly, nullable) NSString *albumTitle MP_API(ios(7.0));

MP_EXTERN NSString * const MPMediaItemPropertyArtist                                                                    // filterable
    MP_API(ios(3.0), tvos(9.0), watchos(5.0), macos(10.12.2));
@property (nonatomic, readonly, nullable) NSString *artist MP_API(ios(7.0));

```
So they are also not defined there, because I think `MP_EXTERN` is a term similar with `extern`?

3. Declare `MPMediaItemPropertyXXX` with linking (**failed**)

So I was thinking about if that could be fixed by manually adding link option, such like [1], then I added following codes,
[1] https://searchfox.org/mozilla-central/rev/7b40f0b246ad0b54975b1525811f2ad599b95f33/toolkit/library/moz.build#75-79

```
LDFLAGS += ["-Wl,-U,_MPMediaItemPropertyTitle"]
LDFLAGS += ["-Wl,-U,_MPMediaItemPropertyArtist"]
LDFLAGS += ["-Wl,-U,_MPMediaItemPropertyAlbumTitle"]
```
The result is that, I could pass the build, however, it failed immediately when I ran Firefox, the error is that,

```
dlopen(/Users/alastor/mozilla-dev/mozilla-central/obj-debug-x86_64-apple-darwin20.1.0/dist/NightlyDebug.app/Contents/MacOS/XUL, 265): Symbol not found: _MPMediaItemPropertyAlbumTitle
  Referenced from: /Users/alastor/mozilla-dev/mozilla-central/obj-debug-x86_64-apple-darwin20.1.0/dist/NightlyDebug.app/Contents/MacOS/XUL
  Expected in: flat namespace
 in /Users/alastor/mozilla-dev/mozilla-central/obj-debug-x86_64-apple-darwin20.1.0/dist/NightlyDebug.app/Contents/MacOS/XUL
Couldn't load XPCOM.
```

4. import <MediaPlayer/MPMediaItem.h> on 12.2+ (**failed**)

Then I thought probably I can't simply override the declaration for things using `MP_EXTERN`, I tried to import the header file directly. 
```
#if defined(MAC_OS_X_VERSION_10_12_2) && MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_12_2
  #import <MediaPlayer/MPMediaItem.h>
#endif
```
That allows me to pass build, and I could also start my Firefox without issue. However, when running to the code where first access to those `MPMediaItemPropertyXXX`, the problem would crash immediately with `EXC_BAD_ACCESS`. I used `lldb` to check if they are still dangering, but I can see they all have value, so I don't really understand this error.

```
(lldb) p MPMediaItemPropertyTitle
warning: `this' is not accessible (substituting 0)
(__NSCFConstantString *) $0 = 0x00007fff8277d3e8 "title"
(lldb) p MPMediaItemPropertyArtist
warning: `this' is not accessible (substituting 0)
(__NSCFConstantString *) $1 = 0x00007fff827802e8 "artist"
(lldb) p MPMediaItemPropertyAlbumTitle
warning: `this' is not accessible (substituting 0)
(__NSCFConstantString *) $2 = 0x00007fff82781ea8 "albumTitle"
```

5. Declare and define `MPMediaItemPropertyXXX` 
Here I went to my last option, force to redefine them manually in `MediaPlayerWrapper.h`

```
#define MPMediaItemPropertyTitle @"title"
#define MPMediaItemPropertyArtist @"artist"
#define MPMediaItemPropertyAlbumTitle @"albumTitle"
```

Okay, this method allows me to build and run Firefox successfully on both the 10.12+ and the 10.11 machine on the try server. However, it would make my gTest fail on the 10.14 machine on the try server. I can successfully pass my gTest on my local environment, but on the 10.14 machine on the try server, it seems that I can't set the value to `MPNowPlayingInfoCenter`'s `nowPlayingInfo`....

Here is my implementation, which works well for me on Big Sur. But on the 10.14 machine on the try server, I can see the results in `DD` are correct, which means I set the value correctly into the local variable `nowPlayingInfo`. However, the results in `DD1` are all empty, which means `MPNowPlayingInfoCenter` didn't update its `nowPlayingInfo`. [2]

[2] https://treeherder.mozilla.org/logviewer?job_id=322229528&repo=try&lineNumber=29394

```
void MediaHardwareKeysEventSourceMacMediaCenter::SetMediaMetadata(
    const dom::MediaMetadataBase& aMetadata) {
  NSMutableDictionary* nowPlayingInfo = [NSMutableDictionary dictionary];
  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mTitle)
                     forKey:MPMediaItemPropertyTitle];
  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mArtist)
                     forKey:MPMediaItemPropertyArtist];
  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mAlbum)
                     forKey:MPMediaItemPropertyAlbumTitle];
  NSLog(@"DD | Title in=%s out=%@", NS_ConvertUTF16toUTF8(aMetadata.mTitle).get(),
        nowPlayingInfo[MPMediaItemPropertyTitle]);
  NSLog(@"DD | Artist=%@", nowPlayingInfo[MPMediaItemPropertyArtist]);
  NSLog(@"DD | Album=%@", nowPlayingInfo[MPMediaItemPropertyAlbumTitle]);
  MPNowPlayingInfoCenter* center =
      (MPNowPlayingInfoCenter*)[mpNowPlayingInfoCenterClass defaultCenter];
  center.nowPlayingInfo = nowPlayingInfo;
  NSLog(@"DD1 | Title=%@", center.nowPlayingInfo[MPMediaItemPropertyTitle]);
  NSLog(@"DD1 | Artist=%@", center.nowPlayingInfo[MPMediaItemPropertyArtist]);
  NSLog(@"DD1 | Album=%@", center.nowPlayingInfo[MPMediaItemPropertyAlbumTitle]);
}
```

Revision 1 by

Alastor Wu [:alwu]

on 2020-11-18 17:25:57 PST

I'm still suffering from the build/link issues, here I'm going to describe the problems I encountered.

---
1. Use `MediaPlayer` framework directly (**failed**)
As we are still using 10.11 on the try server, which is an older SDK, we are not able to find `MediaPlayer` framework to link on that SDK version.

2. Declare `extern ... MPMediaItemPropertyXXX` (**failed**)
Then I tried to define something following in `MediaPlayerWrapper.h`

 ```
extern NSString* const _Nullable MPMediaItemPropertyTitle;
extern NSString* const _Nullable MPMediaItemPropertyArtist;
extern NSString* const _Nullable MPMediaItemPropertyAlbumTitle;
```
On the linking stage, it would show the error of not being able to find those symbols. Those variables are originally defined in `MPMediaItem.h`, which look like that,

```
MP_EXTERN NSString * const MPMediaItemPropertyTitle                                                                     // filterable
    MP_API(ios(3.0), tvos(9.0), watchos(5.0), macos(10.12.2));
@property (nonatomic, readonly, nullable) NSString *title MP_API(ios(7.0));

MP_EXTERN NSString * const MPMediaItemPropertyAlbumTitle
    MP_API(ios(3.0), tvos(9.0), watchos(5.0), macos(10.12.2));                                                          // filterable
@property (nonatomic, readonly, nullable) NSString *albumTitle MP_API(ios(7.0));

MP_EXTERN NSString * const MPMediaItemPropertyArtist                                                                    // filterable
    MP_API(ios(3.0), tvos(9.0), watchos(5.0), macos(10.12.2));
@property (nonatomic, readonly, nullable) NSString *artist MP_API(ios(7.0));

```
So they are also not defined there, because I think `MP_EXTERN` is a term similar with `extern`?

3. Declare `MPMediaItemPropertyXXX` with linking (**failed**)

So I was thinking about if that could be fixed by manually adding link option, such like [1], then I added following codes,
[1] https://searchfox.org/mozilla-central/rev/7b40f0b246ad0b54975b1525811f2ad599b95f33/toolkit/library/moz.build#75-79

```
LDFLAGS += ["-Wl,-U,_MPMediaItemPropertyTitle"]
LDFLAGS += ["-Wl,-U,_MPMediaItemPropertyArtist"]
LDFLAGS += ["-Wl,-U,_MPMediaItemPropertyAlbumTitle"]
```
The result is that, I could pass the build, however, it failed immediately when I ran Firefox, the error is that,

```
dlopen(/Users/alastor/mozilla-dev/mozilla-central/obj-debug-x86_64-apple-darwin20.1.0/dist/NightlyDebug.app/Contents/MacOS/XUL, 265): Symbol not found: _MPMediaItemPropertyAlbumTitle
  Referenced from: /Users/alastor/mozilla-dev/mozilla-central/obj-debug-x86_64-apple-darwin20.1.0/dist/NightlyDebug.app/Contents/MacOS/XUL
  Expected in: flat namespace
 in /Users/alastor/mozilla-dev/mozilla-central/obj-debug-x86_64-apple-darwin20.1.0/dist/NightlyDebug.app/Contents/MacOS/XUL
Couldn't load XPCOM.
```

4. import <MediaPlayer/MPMediaItem.h> on 12.2+ (**failed**)

Then I thought probably I can't simply override the declaration for things using `MP_EXTERN`, I tried to import the header file directly. 
```
#if defined(MAC_OS_X_VERSION_10_12_2) && MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_12_2
  #import <MediaPlayer/MPMediaItem.h>
#endif
```
That allows me to pass build, and I could also start my Firefox without issue. However, when running to the code where first access to those `MPMediaItemPropertyXXX`, the problem would crash immediately with `EXC_BAD_ACCESS`. I used `lldb` to check if they are still dangering, but I can see they all have value, so I don't really understand this error.

```
(lldb) p MPMediaItemPropertyTitle
warning: `this' is not accessible (substituting 0)
(__NSCFConstantString *) $0 = 0x00007fff8277d3e8 "title"
(lldb) p MPMediaItemPropertyArtist
warning: `this' is not accessible (substituting 0)
(__NSCFConstantString *) $1 = 0x00007fff827802e8 "artist"
(lldb) p MPMediaItemPropertyAlbumTitle
warning: `this' is not accessible (substituting 0)
(__NSCFConstantString *) $2 = 0x00007fff82781ea8 "albumTitle"
```

5. Declare and define `MPMediaItemPropertyXXX` (**failed only on the try server gTest**)

Here I went to my last option, force to redefine them manually in `MediaPlayerWrapper.h`

```
#define MPMediaItemPropertyTitle @"title"
#define MPMediaItemPropertyArtist @"artist"
#define MPMediaItemPropertyAlbumTitle @"albumTitle"
```

Okay, this method allows me to build and run Firefox successfully on both the 10.12+ and the 10.11 machine on the try server. However, it would make my gTest fail on the 10.14 machine on the try server. I can successfully pass my gTest on my local environment, but on the 10.14 machine on the try server, it seems that I can't set the value to `MPNowPlayingInfoCenter`'s `nowPlayingInfo`....

Here is my implementation, which works well for me on Big Sur. But on the 10.14 machine on the try server, I can see the results in `DD` are correct, which means I set the value correctly into the local variable `nowPlayingInfo`. However, the results in `DD1` are all empty, which means `MPNowPlayingInfoCenter` didn't update its `nowPlayingInfo`. [2]

[2] https://treeherder.mozilla.org/logviewer?job_id=322229528&repo=try&lineNumber=29394

```
void MediaHardwareKeysEventSourceMacMediaCenter::SetMediaMetadata(
    const dom::MediaMetadataBase& aMetadata) {
  NSMutableDictionary* nowPlayingInfo = [NSMutableDictionary dictionary];
  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mTitle)
                     forKey:MPMediaItemPropertyTitle];
  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mArtist)
                     forKey:MPMediaItemPropertyArtist];
  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mAlbum)
                     forKey:MPMediaItemPropertyAlbumTitle];
  NSLog(@"DD | Title in=%s out=%@", NS_ConvertUTF16toUTF8(aMetadata.mTitle).get(),
        nowPlayingInfo[MPMediaItemPropertyTitle]);
  NSLog(@"DD | Artist=%@", nowPlayingInfo[MPMediaItemPropertyArtist]);
  NSLog(@"DD | Album=%@", nowPlayingInfo[MPMediaItemPropertyAlbumTitle]);
  MPNowPlayingInfoCenter* center =
      (MPNowPlayingInfoCenter*)[mpNowPlayingInfoCenterClass defaultCenter];
  center.nowPlayingInfo = nowPlayingInfo;
  NSLog(@"DD1 | Title=%@", center.nowPlayingInfo[MPMediaItemPropertyTitle]);
  NSLog(@"DD1 | Artist=%@", center.nowPlayingInfo[MPMediaItemPropertyArtist]);
  NSLog(@"DD1 | Album=%@", center.nowPlayingInfo[MPMediaItemPropertyAlbumTitle]);
}
```

Revision 2 by

Alastor Wu [:alwu]

on 2020-11-18 17:29:05 PST

I'm still suffering from the build/link issues, here I'm going to describe the problems I encountered.

---
1. Use `MediaPlayer` framework directly (**failed**)
As we are still using 10.11 on the try server, which is an older SDK, we are not able to find `MediaPlayer` framework to link on that SDK version.

2. Declare `extern ... MPMediaItemPropertyXXX` (**failed**)
Then I tried to define something following in `MediaPlayerWrapper.h`

 ```
extern NSString* const _Nullable MPMediaItemPropertyTitle;
extern NSString* const _Nullable MPMediaItemPropertyArtist;
extern NSString* const _Nullable MPMediaItemPropertyAlbumTitle;
```
On the linking stage, it would show the error of not being able to find those symbols. Those variables are originally defined in `MPMediaItem.h`, which look like that,

```
MP_EXTERN NSString * const MPMediaItemPropertyTitle                                                                     // filterable
    MP_API(ios(3.0), tvos(9.0), watchos(5.0), macos(10.12.2));
@property (nonatomic, readonly, nullable) NSString *title MP_API(ios(7.0));

MP_EXTERN NSString * const MPMediaItemPropertyAlbumTitle
    MP_API(ios(3.0), tvos(9.0), watchos(5.0), macos(10.12.2));                                                          // filterable
@property (nonatomic, readonly, nullable) NSString *albumTitle MP_API(ios(7.0));

MP_EXTERN NSString * const MPMediaItemPropertyArtist                                                                    // filterable
    MP_API(ios(3.0), tvos(9.0), watchos(5.0), macos(10.12.2));
@property (nonatomic, readonly, nullable) NSString *artist MP_API(ios(7.0));

```
So they are also not defined there, because I think `MP_EXTERN` is a term similar with `extern`?

3. Declare `MPMediaItemPropertyXXX` with linking (**failed**)

So I was thinking about if that could be fixed by manually adding link option, such like [1], then I added following codes,
[1] https://searchfox.org/mozilla-central/rev/7b40f0b246ad0b54975b1525811f2ad599b95f33/toolkit/library/moz.build#75-79

```
LDFLAGS += ["-Wl,-U,_MPMediaItemPropertyTitle"]
LDFLAGS += ["-Wl,-U,_MPMediaItemPropertyArtist"]
LDFLAGS += ["-Wl,-U,_MPMediaItemPropertyAlbumTitle"]
```
The result is that, I could pass the build, however, it failed immediately when I ran Firefox, the error is that,

```
dlopen(/Users/alastor/mozilla-dev/mozilla-central/obj-debug-x86_64-apple-darwin20.1.0/dist/NightlyDebug.app/Contents/MacOS/XUL, 265): Symbol not found: _MPMediaItemPropertyAlbumTitle
  Referenced from: /Users/alastor/mozilla-dev/mozilla-central/obj-debug-x86_64-apple-darwin20.1.0/dist/NightlyDebug.app/Contents/MacOS/XUL
  Expected in: flat namespace
 in /Users/alastor/mozilla-dev/mozilla-central/obj-debug-x86_64-apple-darwin20.1.0/dist/NightlyDebug.app/Contents/MacOS/XUL
Couldn't load XPCOM.
```

4. import <MediaPlayer/MPMediaItem.h> on 12.2+ (**failed**)

Then I thought probably I can't simply override the declaration for things using `MP_EXTERN`, I tried to import the header file directly. 
```
#if defined(MAC_OS_X_VERSION_10_12_2) && MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_12_2
  #import <MediaPlayer/MPMediaItem.h>
#endif
```
That allows me to pass build, and I could also start my Firefox without issue. However, when running to the code where first access to those `MPMediaItemPropertyXXX`, the problem would crash immediately with `EXC_BAD_ACCESS`. I used `lldb` to check if they are still dangling, but I can see they all have value, so I don't really understand this error.

```
(lldb) p MPMediaItemPropertyTitle
warning: `this' is not accessible (substituting 0)
(__NSCFConstantString *) $0 = 0x00007fff8277d3e8 "title"
(lldb) p MPMediaItemPropertyArtist
warning: `this' is not accessible (substituting 0)
(__NSCFConstantString *) $1 = 0x00007fff827802e8 "artist"
(lldb) p MPMediaItemPropertyAlbumTitle
warning: `this' is not accessible (substituting 0)
(__NSCFConstantString *) $2 = 0x00007fff82781ea8 "albumTitle"
```

5. Declare and define `MPMediaItemPropertyXXX` (**failed only on the try server gTest**)

Here I went to my last option, force to redefine them manually in `MediaPlayerWrapper.h`

```
#define MPMediaItemPropertyTitle @"title"
#define MPMediaItemPropertyArtist @"artist"
#define MPMediaItemPropertyAlbumTitle @"albumTitle"
```

Okay, this method allows me to build and run Firefox successfully on both the 10.12+ and the 10.11 machine on the try server. However, it would make my gTest fail on the 10.14 machine on the try server. I can successfully pass my gTest on my local environment, but on the 10.14 machine on the try server, it seems that I can't set the value to `MPNowPlayingInfoCenter`'s `nowPlayingInfo`....

Here is my implementation, which works well for me on Big Sur. But on the 10.14 machine on the try server, I can see the results in `DD` are correct, which means I set the value correctly into the local variable `nowPlayingInfo`. However, the results in `DD1` are all empty, which means `MPNowPlayingInfoCenter` didn't update its `nowPlayingInfo`. [2]

[2] https://treeherder.mozilla.org/logviewer?job_id=322229528&repo=try&lineNumber=29394

```
void MediaHardwareKeysEventSourceMacMediaCenter::SetMediaMetadata(
    const dom::MediaMetadataBase& aMetadata) {
  NSMutableDictionary* nowPlayingInfo = [NSMutableDictionary dictionary];
  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mTitle)
                     forKey:MPMediaItemPropertyTitle];
  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mArtist)
                     forKey:MPMediaItemPropertyArtist];
  [nowPlayingInfo setObject:nsCocoaUtils::ToNSString(aMetadata.mAlbum)
                     forKey:MPMediaItemPropertyAlbumTitle];
  NSLog(@"DD | Title in=%s out=%@", NS_ConvertUTF16toUTF8(aMetadata.mTitle).get(),
        nowPlayingInfo[MPMediaItemPropertyTitle]);
  NSLog(@"DD | Artist=%@", nowPlayingInfo[MPMediaItemPropertyArtist]);
  NSLog(@"DD | Album=%@", nowPlayingInfo[MPMediaItemPropertyAlbumTitle]);
  MPNowPlayingInfoCenter* center =
      (MPNowPlayingInfoCenter*)[mpNowPlayingInfoCenterClass defaultCenter];
  center.nowPlayingInfo = nowPlayingInfo;
  NSLog(@"DD1 | Title=%@", center.nowPlayingInfo[MPMediaItemPropertyTitle]);
  NSLog(@"DD1 | Artist=%@", center.nowPlayingInfo[MPMediaItemPropertyArtist]);
  NSLog(@"DD1 | Album=%@", center.nowPlayingInfo[MPMediaItemPropertyAlbumTitle]);
}
```

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