Re: Incorrect duration of some streamed audio files.

Aristide · ‎02-11-2022

Hello,
I have a problem with some audio files.
To be able to read them correctly on an audio player (in my case on android) you have to be able to determine the duration. for some files the duration returned is not correct. With android mediaplayer 0 ms.
I did the tests through a temporary link or a sharing link.
When I download the file locally then the returned duration is correct.

Any idea?

NB: Tested with mp3 files.

Greg-DB · ‎02-11-2022

It sounds like this may be because we recently updated the server back-end for some types of Dropbox links to use "Transfer-Encoding: chunked" (and accordingly not return the "Content-Length" response header) on HTTP/1.1. HTTP clients should automatically handle this, but it's possible yours doesn't.

Are you able to retrieve any specific error message or output from your HTTP client? That would help confirm that.

If that's the issue, you should update your client/code to support "Transfer-Encoding: chunked" and not assume the "Content-Length" response header will be present. Or, switch to HTTP/2, where the "Content-Length" response header should be present.

Aristide · ‎02-12-2022

The client in my case is the one integrated in the native android player.
What I can see so far:
- not all files are affected.
- the file is not corrupted because readable with the link:
- curiously, the meta data duration which are contained in the first bytes of the audio file, is not correct when I partially download the file (usually the first 1000 KB) while the other meta datas are ok (title, album, art etc.).

Response headers for a file where the duration is correctly returned:

accept-ranges: bytes
    cache-control: max-age=60
    content-disposition: attachment; filename="Isaac Delusion - Midnight Sun.mp3"; filename*=UTF-8''Isaac%20Delusion%20-%20Midnight%20Sun.mp3
    content-security-policy: sandbox
    pragma: public
    referrer-policy: no-referrer
    vary: Origin, Accept-Encoding
    x-content-security-policy: sandbox
    x-content-type-options: nosniff
    x-robots-tag: noindex, nofollow, noimageindex
    x-server-response-time: 46
    x-webkit-csp: sandbox
    content-type: application/json
    accept-encoding: identity,gzip
    date: Sat, 12 Feb 2022 11:30:52 GMT
    server: envoy
    strict-transport-security: max-age=31536000; includeSubDomains; preload
    x-robots-tag: noindex, nofollow, noimageindex
    content-encoding: gzip
    x-dropbox-response-origin: far_remote
    x-dropbox-request-id: a76b8827cea24632ad411939dea04550

Response headers for a file where the returned duration is not correct:

accept-ranges: bytes
    cache-control: max-age=60
    content-disposition: attachment; filename="Pixies - Dig for Fire.mp3"; filename*=UTF-8''Pixies%20-%20Dig%20for%20Fire.mp3
    content-security-policy: sandbox
    pragma: public
    referrer-policy: no-referrer
    vary: Origin, Accept-Encoding
    x-content-security-policy: sandbox
    x-content-type-options: nosniff
    x-robots-tag: noindex, nofollow, noimageindex
    x-server-response-time: 47
    x-webkit-csp: sandbox
    content-type: application/json
    accept-encoding: identity,gzip
    date: Sat, 12 Feb 2022 11:28:20 GMT
    server: envoy
    strict-transport-security: max-age=31536000; includeSubDomains; preload
    x-robots-tag: noindex, nofollow, noimageindex
    content-encoding: gzip
    x-dropbox-response-origin: far_remote
    x-dropbox-request-id: f63eef26b69d49c18ebb96ca9e1d4ffc

In both cases I don't have a "content-length" header?.

I noticed content-type: application/json and not audio/mpeg why?
To get this headers in response I used okhttp client.

In fact, this problem appeared recently.

same result if I force the protocol with HTTP/2 with:

public static OkHttpClient getHttp2Client(){
        ConnectionPool connectionPool = new ConnectionPool();
        return new OkHttpClient.Builder()
                .followRedirects(true)
                .protocols(Arrays.asList(Protocol.HTTP_2,Protocol.HTTP_1_1))
                .retryOnConnectionFailure(true)
                .connectionPool(connectionPool)
                .build();
    }

"you should update your client/code to support "Transfer-Encoding: chunked"

Does this mean that I have to add "Transfer-Encoding: chunked" as a header to my request?

Aristide · ‎02-14-2022

It seems that this "bug" is reported in these posts:

https://www.dropboxforum.com/t5/Dropbox-API-Support-Feedback/HEAD-request-to-get-Content-Type-of-sha...

https://www.dropboxforum.com/t5/Dropbox-API-Support-Feedback/Functionality-changes/td-p/575628

I confirm that files whose duration cannot be determined by android's mediaPlayer are not seekable.

It seems to me that the DropBox android app always downloads files locally before playing them?

Greg-DB · ‎02-14-2022

Thanks for following up. I can't offer any details on the implementation of the Dropbox Android app itself, but I'll follow up with any updates on the reports you linked to.

Greg-DB · ‎02-14-2022

Update: in order to temporarily accommodate clients that don’t properly support automatically handling “Transfer-Encoding: chunked”, we’re temporarily rolling back this change, so that these links will no longer use “Transfer-Encoding: chunked” and will instead return “Content-Length” on HTTP/1.1. We will begin rolling that out starting around 2/17. That will be in place until around 3/1. At that point, we will begin using “Transfer-Encoding: chunked” and no longer returning “Content-Length” on HTTP/1.1 again.

Going forward, please ensure that your clients are able to automatically handle both chunked encoding and non-chunked encoding automatically.

Aristide · ‎02-15-2022

Thanks Greg-DB for the follow up.

But there will therefore be a problem with Android because at this stage, I don't see how it is possible to force the client integrated into the mediaPlayer to handle both chunked encoding and non-chunked encoding automatically, it is not accessible, or so by a method that I do not know.

It is possible to partially circumvent the duration problem by calculating with file size and bitrate (for MP3 files with CBR) but not to circumvent the ability to seek .

Is there a way to get feedback from the developers of the DropBox app for android?

Greg-DB · ‎02-15-2022

Thanks for the additional context. I cannot provide support for third party clients unfortunately though, so please refer to the documentation/support resources for the client.

Also, no, I can't offer a way to get help from the developers of the official Dropbox Android app itself.

Apologies I can't be of more help in that regard!

Greg-DB · ‎03-11-2022

Update: the team has been able to complete some further updates to our infrastructure to be able to support the previous non-chunked behavior going forward indefinitely. That means that we plan to continue returning Content-Length (and not 'Transfer-Encoding: chunked') in the future and will not be reverting this as previously planned. (Regardless, for HTTP compatibility in general, we still recommend you make sure your HTTP clients support both types.) Hope this helps!