shaka player has issue to connect to repro mpd file. But I can repro this issue on Dash-if player. On Mac, I do see muxed source freeze while audio is playing normally. the un-muxed source play without issue.
On Windows, neither video (muxed and un-muxed) is loaded, Dash-if player shows black. 
give to wolenetz@ to take a look.

@#2, FYI - for shaka player, I suspect you just need to load it with http, not https, since the mpd is http and mixed-content MSE is not allowed.

Case #1: confirmed repro on Linux 52.0.2743.116 (Official Build) (64-bit) using (http) shaka AND dash-if player and muxed mpd (#1 in original post) (audio plays continuously for 20 second duration, but video frame is frozen in the following approximate ranges: [0,7] [10,17].

Case #2: confirmed no repro (also linux, same build) using (http) dash-if player and unmuxed mpd (#2 in original post). Both audio and video play continuously for the 20 second duration.

I suspect it's something in the video stream itself. Even in the unmuxed case, the dash-if player's console logs show some strange behavior:

Correction to comment #4: Case #2 has a problem, too: It plays continuously from time ~8 seconds to 20 seconds. It immediately starts at time ~8, versus the muxed case which shows the first video frame for all of the first ~7 seconds of audio.) Both appear to be by design in the implementation and the dash-if player.

<video> loadedmetadata 
Debug.js:1 Starting playback at offset: 0 
Debug.js:1 [audio] Got enough buffer to start. 
Debug.js:1 [audio] Buffered Range: 0 - 10.050411 
Debug.js:1 [video] Buffered Range: 7.2 - 10 
Debug.js:1 Do seek: 7.2 
Debug.js:1 <video> seek 
Debug.js:1 [video] Got enough buffer to start. 
Debug.js:1 [video] seek: 7.2 
Debug.js:1 [audio] seek: 7.2 

How was this mpd and associated media produced? Is it expected for the first video keyframe to be at time 7? 

The issue is not about the start from 7s. It's about the freezing that occurs at [10-17]. Shouldn't decoder use the key frame it got earlier to play [7-10] s video?

* as the unmuxed content also uses the previous key frame and don't freeze for [10-17] s

Thank you for providing more feedback. Adding "Needs-Review" label for tracking.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

add Joey since shaka not able to play neither muxed or unmuxed video.
architagrawal1993@gmail.com,can you answer wolenetz@'s question on #5? 
Is this issue repro on other muxed video? 

Aside from whatever the decoder issue is, Shaka can play the muxed manifest:

http://shaka-player-demo.appspot.com/demo/?play;asset=http://de9b7h88wgj5l.cloudfront.net/static/arcagw/muxed/sample.mpd

The unmuxed manifest, however, is out of spec.  All of your AdaptationSets and Representations have id="1", which is why Shaka Player only shows audio and no video:

http://shaka-player-demo.appspot.com/demo/?play;asset=http://de9b7h88wgj5l.cloudfront.net/static/arcagw/sample.mpd

According to the DASH spec (ISO/IEC 23009-1:2014) sections 5.3.3.2 and 5.3.5.2, Representation ids and AdaptationSet ids must be unique within the Period.  Please fix your content or file a bug on your encoder vender.

I don't have any other content that doesn't have keyframe at the beginning of fragment. Hence, I am not sure if I can repro this issue with any other content. 

Regarding issue with shaka player, I am seeing it just plays the audio not video for the muxed content. Also, I agree there is a problem with the unmuxed content manifest file but since the issue is with muxed source buffer, we can ignore this.

joeyparrish@, repro url for muxed manifest in #10 shows only audio is played, video is not played in the first 7 seconds. Is it a player bug? can you confirm?

Not a player bug.  The browser's decoder doesn't seem to like the content.  We feed content to the browser, which decodes and renders.  The player could not play audio while freezing video even if it wanted to.

matt, sorry I have to give this bug back to you. as per #13, it is a browser bug that the muxed manifest in #10 couldn't play video in the first 7 seconds while audio is played normally. Please re-assign appropriately.

Any status on this?

Cleaning up sheriffbot label "Needs-Review" label as a part of modified "Needs-Feedback" sheriffbot rule. [ref bug for cleanup 684919]