Remove pts adjustments in stream

[uvjustin]

Proposed change

Adjusting the incoming packet DTS/PTS of the audio and video streams to start from 0 based on the first packet of each stream received seems to be unnecessary for the hls segments and starting both from 0 may actually cause a slightly inaccurate A/V sync, as there might be a slight offset between the audio and video segments. Assuming the input audio and video streams are consistent, we can just use the original DTS/PTS values of the input streams. This PR removes the DTS/PTS adjustments in the stream worker and makes the peek_first_pts function slightly more readable.
In recorder, we still need to adjust the dts/pts to 0 for the video stream, but we should also use a common basis for adjustment for the audio stream to avoid the minor A/V sync issue.

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[probot-home-assistant]

Hey there @hunterjm, mind taking a look at this pull request as its been labeled with an integration (stream) you are listed as a codeowner for? Thanks!
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[hunterjm]

Does this work? I believe the reason I had to add the seek in the first place is because after initial muxing the pointer in the BytesIO was at the end, so when calling av.open it didn't read the stream properly.

[uvjustin]

Hmm, this seems to work on my end. Maybe you can test it out when you get a chance? That said, there does seem to be a fair amount of seemingly random stuff we have in the component that's actually there for good reason :-)
Edit: Given that you remember that we need it we should be extra careful about it. You told me the same thing about the monotonic dts check, and we ended up getting endless complaints about a few warning messages...

[hunterjm]

It's possible it was added back when I wasn't closing the output container (which PyAV didn't allow you to do until a recent version bump). Now that we are, it's entirely possible that the act of closing the stream resets it automatically.
edit: I can try to test later tonight to make sure.

[hunterjm]

Verified locally. Looks good.