From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C0A84C52D6F for ; Thu, 8 Aug 2024 11:29:24 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=mn90FOHQ; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4WflDz1rV0z2xrC for ; Thu, 8 Aug 2024 21:29:23 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=mn90FOHQ; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=linux.intel.com (client-ip=192.198.163.8; helo=mgamail.intel.com; envelope-from=pierre-louis.bossart@linux.intel.com; receiver=lists.ozlabs.org) X-Greylist: delayed 64 seconds by postgrey-1.37 at boromir; Thu, 08 Aug 2024 21:28:42 AEST Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4WflDB6X7yz2xFn for ; Thu, 8 Aug 2024 21:28:42 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1723116523; x=1754652523; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=VmB/6QS1FQ+RUMXWz253lu/uSyqhXxIJWMc4iBtGTIA=; b=mn90FOHQRsXVGesi0fsMZqbkeKfB6m3srDcsHCWpPI97SUCmS9cBM6wS xnSAdbHUZJZpBPwrDqON/tUWyV9o5GkF6GQ8S7LFQ2hlmn759AOQ/6+8T /TEa88cX6YTt+ZlVblINPWTwEF7wQKSTy/3SJQxtRdhq7krxcnDakNRtx nCndG7ylWkjYkbRQDnesrtxhQEt1m2MH5lqgd/lE6EmS2/Xzgfg3Xkkfw X5MwgqN1q2P023wQRxz30j71CNOrYRpVNBTjZNxnJRCLO2wZ0yOD+LO3B MRQJnEhOaP8paNs9qd3GwXDIgw2/N5t9q4lOMVQp7ExzHbsvc/gVzWmOk Q==; X-CSE-ConnectionGUID: 6jJ7e0cbRlapAERFa2tvFA== X-CSE-MsgGUID: mKze557tRdOq7xFUgMpxKw== X-IronPort-AV: E=McAfee;i="6700,10204,11157"; a="38742182" X-IronPort-AV: E=Sophos;i="6.09,272,1716274800"; d="scan'208";a="38742182" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Aug 2024 04:27:36 -0700 X-CSE-ConnectionGUID: CU7zVrCdQxe/FdISjC4yqQ== X-CSE-MsgGUID: oN5J9gC0QvOy35eh/N/PBA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,272,1716274800"; d="scan'208";a="61575228" Received: from kniemiec-mobl1.ger.corp.intel.com (HELO [10.245.246.169]) ([10.245.246.169]) by fmviesa005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Aug 2024 04:27:32 -0700 Message-ID: Date: Thu, 8 Aug 2024 13:27:29 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 1/6] ALSA: compress: add Sample Rate Converter codec support To: Shengjiu Wang References: <1722940003-20126-1-git-send-email-shengjiu.wang@nxp.com> <1722940003-20126-2-git-send-email-shengjiu.wang@nxp.com> Content-Language: en-US From: Pierre-Louis Bossart In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alsa-devel@alsa-project.org, lgirdwood@gmail.com, Xiubo.Lee@gmail.com, linux-kernel@vger.kernel.org, Shengjiu Wang , linuxppc-dev@lists.ozlabs.org, tiwai@suse.com, linux-sound@vger.kernel.org, perex@perex.cz, nicoleotsuka@gmail.com, vkoul@kernel.org, broonie@kernel.org, festevam@gmail.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 8/8/24 11:17, Shengjiu Wang wrote: > On Tue, Aug 6, 2024 at 7:25 PM Pierre-Louis Bossart > wrote: >> >> >> >> On 8/6/24 12:26, Shengjiu Wang wrote: >>> Add Sample Rate Converter(SRC) codec support, define the output >>> format and rate for SRC. >>> >>> Signed-off-by: Shengjiu Wang >>> --- >>> include/uapi/sound/compress_offload.h | 2 ++ >>> include/uapi/sound/compress_params.h | 9 ++++++++- >>> 2 files changed, 10 insertions(+), 1 deletion(-) >>> >>> diff --git a/include/uapi/sound/compress_offload.h b/include/uapi/sound/compress_offload.h >>> index 98772b0cbcb7..8b2b72f94e26 100644 >>> --- a/include/uapi/sound/compress_offload.h >>> +++ b/include/uapi/sound/compress_offload.h >>> @@ -112,10 +112,12 @@ struct snd_compr_codec_caps { >>> * end of the track >>> * @SNDRV_COMPRESS_ENCODER_DELAY: no of samples inserted by the encoder at the >>> * beginning of the track >>> + * @SNDRV_COMPRESS_SRC_RATIO_MOD: Resampling Ratio Modifier for sample rate converter >>> */ >>> enum sndrv_compress_encoder { >>> SNDRV_COMPRESS_ENCODER_PADDING = 1, >>> SNDRV_COMPRESS_ENCODER_DELAY = 2, >>> + SNDRV_COMPRESS_SRC_RATIO_MOD = 3, >>> }; >> >> this sounds wrong to me. The sample rate converter is not an "encoder", >> and the properties for padding/delay are totally specific to an encoder >> function. > > There is only decoder and encoder definition for compress, I know > it is difficult to add SRC to encoder or decoder classification, > SRC is a Post Processing. I hope you can have a recommandation I don't. I think we're blurring layers in a really odd way. The main reason why the compress API was added is to remove the byte-to-time conversions. But that's clearly not useful for a post-processing of PCM data, where the bitrate is constant. It really feels like we're adding this memory-to-memory API to the compress framework because we don't have anything else available, not because it makes sense to do so. Then there's the issue of parameters, we chose to only add parameters for standard encoders/decoders. Post-processing is highly specific and the parameter definitions varies from one implementation to another - and usually parameters are handled in an opaque way with binary controls. This is best handled with a UUID that needs to be known only to applications and low-level firmware/hardware, the kernel code should not have to be modified for each and every processing and to add new parameters. It just does not scale and it's unmaintainable. At the very least if you really want to use this compress API, extend it to use a non-descript "UUID-defined" type and an opaque set of parameters with this UUID passed in a header.