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From: "Andrew Fish" <afish@apple.com>
To: edk2-devel-groups-io <devel@edk2.groups.io>,
	Leif Lindholm <leif@nuviainc.com>
Cc: Ethin Probst <harlydavidsen@gmail.com>,
	Michael Brown <mcb30@ipxe.org>,
	Mike Kinney <michael.d.kinney@intel.com>,
	Laszlo Ersek <lersek@redhat.com>,
	"Desimone, Nathaniel L" <nathaniel.l.desimone@intel.com>,
	Rafael Rodrigues Machado <rafaelrodrigues.machado@gmail.com>,
	Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [edk2-devel] VirtIO Sound Driver (GSoC 2021)
Date: Fri, 16 Apr 2021 10:03:51 -0700	[thread overview]
Message-ID: <10E3436C-D743-4B2F-8E4B-7AD93B82FC92@apple.com> (raw)
In-Reply-To: <20210416113447.GG1664@vanye>



> On Apr 16, 2021, at 4:34 AM, Leif Lindholm <leif@nuviainc.com> wrote:
> 
> Hi Ethin,
> 
> I think we also want to have a SetMode function, even if we don't get
> around to implement proper support for it as part of GSoC (although I
> expect at least for virtio, that should be pretty straightforward).
> 

Leif,

I’m think if we have an API to load the buffer and a 2nd API to play the buffer an optional 3rd API could configure the streams. 

> It's quite likely that speech for UI would be stored as 8kHz (or
> 20kHz) in some systems, whereas the example for playing a tune in GRUB
> would more likely be a 44.1 kHz mp3/wav/ogg/flac.
> 
> For the GSoC project, I think it would be quite reasonable to
> pre-generate pure PCM streams for testing rather than decoding
> anything on the fly.
> 
> Porting/writing decoders is really a separate task from enabling the
> output. I would much rather see USB *and* HDA support able to play pcm
> streams before worrying about decoding.
> 

I agree it might turn out it is easier to have the text to speech code just encode a PCM directly. 

Thanks,

Andrew Fish

> /
>    Leif
> 
> On Fri, Apr 16, 2021 at 00:33:06 -0500, Ethin Probst wrote:
>> Thanks for that explanation (I missed Mike's message). Earlier I sent
>> a summary of those things that we can agree on: mainly, that we have
>> mute, volume control, a load buffer, (maybe) an unload buffer, and a
>> start/stop stream function. Now that I fully understand the
>> ramifications of this I don't mind settling for a specific format and
>> sample rate, and signed 16-bit PCM audio is, I think, the most widely
>> used one out there, besides 64-bit floating point samples, which I've
>> only seen used in DAWs, and that's something we don't need.
>> Are you sure you want the firmware itself to handle the decoding of
>> WAV audio? I can make a library class for that, but I'll definitely
>> need help with the security aspect.
>> 
>> On 4/16/21, Andrew Fish via groups.io <afish=apple.com@groups.io> wrote:
>>> 
>>> 
>>>> On Apr 15, 2021, at 5:59 PM, Michael Brown <mcb30@ipxe.org> wrote:
>>>> 
>>>> On 16/04/2021 00:42, Ethin Probst wrote:
>>>>> Forcing a particular channel mapping, sample rate and sample format on
>>>>> everyone would complicate application code. From an application point
>>>>> of view, one would, with that type of protocol, need to do the
>>>>> following:
>>>>> 1) Load an audio file in any audio file format from any storage
>>>>> mechanism.
>>>>> 2) Decode the audio file format to extract the samples and audio
>>>>> metadata.
>>>>> 3) Resample the (now decoded) audio samples and convert (quantize) the
>>>>> audio samples into signed 16-bit PCM audio.
>>>>> 4) forward the samples onto the EFI audio protocol.
>>>> 
>>>> You have made an incorrect assumption that there exists a requirement to
>>>> be able to play audio files in arbitrary formats.  This requirement does
>>>> not exist.
>>>> 
>>>> With a protocol-mandated fixed baseline set of audio parameters (sample
>>>> rate etc), what would happen in practice is that the audio files would be
>>>> encoded in that format at *build* time, using tools entirely external to
>>>> UEFI.  The application code is then trivially simple: it just does "load
>>>> blob, pass blob to audio protocol".
>>>> 
>>> 
>>> 
>>> Ethin,
>>> 
>>> Given the goal is an industry standard we value interoperability more that
>>> flexibility.
>>> 
>>> How about another use case. Lets say the Linux OS loader (Grub) wants to
>>> have an accessible UI so it decides to sore sound files on the EFI System
>>> Partition and use our new fancy UEFI Audio Protocol to add audio to the OS
>>> loader GUI. So that version of Grub needs to work on 1,000 of different PCs
>>> and a wide range of UEFI Audio driver implementations. It is a much easier
>>> world if Wave PCM 16 bit just works every place. You could add a lot of
>>> complexity and try to encode the audio on the fly, maybe even in Linux
>>> proper but that falls down if you are booting from read only media like a
>>> DVD or backup tape (yes people still do that in server land).
>>> 
>>> The other problem with flexibility is you just made the test matrix very
>>> large for every driver that needs to get implemented. For something as
>>> complex as Intel HDA how you hook up the hardware and what CODECs you use
>>> may impact the quality of the playback for a given board. Your EFI is likely
>>> going to pick a single encoding at that will get tested all the time if your
>>> system has audio, but all 50 other things you support not so much. So that
>>> will required testing, and some one with audiophile ears (or an AI program)
>>> to test all the combinations. I’m not kidding I get BZs on the quality of
>>> the boot bong on our systems.
>>> 
>>> 
>>>>> typedef struct EFI_SIMPLE_AUDIO_PROTOCOL {
>>>>>  EFI_SIMPLE_AUDIO_PROTOCOL_RESET Reset;
>>>>>  EFI_SIMPLE_AUDIO_PROTOCOL_START Start;
>>>>>  EFI_SIMPLE_AUDIO_PROTOCOL_STOP Stop;
>>>>> } EFI_SIMPLE_AUDIO_PROTOCOL;
>>>> 
>>>> This is now starting to look like something that belongs in boot-time
>>>> firmware.  :)
>>>> 
>>> 
>>> I think that got a little too simple I’d go back and look at the example I
>>> posted to the thread but add an API to load the buffer, and then play the
>>> buffer (that way we can an API in the future to twiddle knobs). That API
>>> also implements the async EFI interface. Trust me the 1st thing that is
>>> going to happen when we add audio is some one is going to complain in xyz
>>> state we should mute audio, or we should honer audio volume and mute
>>> settings from setup, or from values set in the OS. Or some one is going to
>>> want the volume keys on the keyboard to work in EFI.
>>> 
>>> Also if you need to pick apart the Wave PCM 16 byte file to feed it into the
>>> audio hardware that probably means we should have a library that does that
>>> work, so other Audio drivers can share that code. Also having a library
>>> makes it easier to write a unit test. We need to be security conscious as we
>>> need to treat the Audo file as attacker controlled data.
>>> 
>>> Thanks,
>>> 
>>> Andrew Fish
>>> 
>>>> Michael
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>> 
>> 
>> -- 
>> Signed,
>> Ethin D. Probst
> 
> 
> 
> 
> 


  reply	other threads:[~2021-04-16 17:03 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-29 20:28 VirtIO Sound Driver (GSoC 2021) Ethin Probst
2021-03-30  3:17 ` [edk2-devel] " Nate DeSimone
2021-03-30 14:41   ` Ethin Probst
2021-03-31  6:34     ` Nate DeSimone
2021-03-30 21:50 ` Rafael Machado
2021-03-30 22:12   ` Ethin Probst
     [not found]   ` <16713E6D64EE917D.25648@groups.io>
2021-03-31  0:01     ` Ethin Probst
2021-03-31  5:02       ` Andrew Fish
2021-03-31  6:41         ` Nate DeSimone
2021-04-01  5:05           ` Ethin Probst
2021-04-05  4:42             ` Andrew Fish
2021-04-05  4:43               ` Ethin Probst
2021-04-05  5:10                 ` Andrew Fish
2021-04-06 14:16           ` Laszlo Ersek
2021-04-06 15:17             ` Ethin Probst
2021-04-13 12:28               ` Leif Lindholm
2021-04-13 14:16                 ` Andrew Fish
2021-04-13 16:53                   ` Ethin Probst
2021-04-13 21:38                     ` Andrew Fish
2021-04-13 23:47                       ` Ethin Probst
     [not found]                       ` <16758FB6436B1195.32393@groups.io>
2021-04-14  1:20                         ` Ethin Probst
2021-04-14  3:52                           ` Andrew Fish
2021-04-14 20:47                             ` Ethin Probst
2021-04-14 22:30                               ` Michael D Kinney
2021-04-14 23:54                                 ` Andrew Fish
2021-04-15  4:01                                   ` Ethin Probst
2021-04-15  4:58                                     ` Andrew Fish
2021-04-15  5:28                                       ` Ethin Probst
2021-04-15 12:07                                         ` Michael Brown
2021-04-15 16:42                                           ` Andrew Fish
2021-04-15 20:11                                             ` Ethin Probst
2021-04-15 22:35                                               ` Andrew Fish
2021-04-15 23:42                                                 ` Ethin Probst
2021-04-16  0:59                                                   ` Michael Brown
2021-04-16  5:13                                                     ` Andrew Fish
2021-04-16  5:33                                                       ` Ethin Probst
2021-04-16 11:34                                                         ` Leif Lindholm
2021-04-16 17:03                                                           ` Andrew Fish [this message]
2021-04-16 17:45                                                             ` Ethin Probst
2021-04-16 17:55                                                               ` Ethin Probst
2021-04-16 18:09                                                                 ` Andrew Fish
2021-04-16 23:50                                                                   ` Ethin Probst
2021-04-16 18:02                                                               ` Andrew Fish
2021-04-17 16:51                                                               ` Marvin Häuser
2021-04-17 17:31                                                                 ` Andrew Fish
2021-04-17 18:04                                                                   ` Marvin Häuser
2021-04-18  8:55                                                                     ` Ethin Probst
2021-04-18 15:22                                                                       ` Andrew Fish
2021-04-18 19:11                                                                         ` Marvin Häuser
2021-04-18 19:22                                                                           ` Marvin Häuser
2021-04-18 21:00                                                                             ` Andrew Fish
2021-04-16 13:22                                                   ` Marvin Häuser
2021-04-16 14:34                                                     ` Andrew Fish
2021-04-16 15:03                                                       ` Marvin Häuser
     [not found]                                                 ` <16762C957671127A.12361@groups.io>
2021-04-16  0:59                                                   ` Ethin Probst
2021-04-16  1:03                                                     ` Michael Brown
2021-04-16  2:06                                                       ` Ethin Probst
2021-04-16  3:48                                                       ` Andrew Fish
2021-04-16  4:29                                                         ` Ethin Probst
2021-04-15  9:51                                     ` Laszlo Ersek
2021-04-15 16:01                                       ` Andrew Fish
2021-04-04 22:05 ` Marvin Häuser

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