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[88.67.245.126]) by smtp.gmail.com with ESMTPSA id bl8-20020a170906c24800b00949691d3183sm3554040ejb.36.2023.04.15.02.51.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 15 Apr 2023 02:51:44 -0700 (PDT) Date: Sat, 15 Apr 2023 11:51:43 +0200 From: Luke Koch To: Muni Sekhar Subject: Re: ALSA: arecord : silennce recorded as 0x80 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-MailFrom: lu.ale.koch@gmail.com X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1 Message-ID-Hash: QYNO4UWXT5H2HUHQHZ2Q5JARKAAI5YI3 X-Message-ID-Hash: QYNO4UWXT5H2HUHQHZ2Q5JARKAAI5YI3 X-Mailman-Approved-At: Tue, 18 Apr 2023 11:51:27 +0000 CC: LKML , alsa-devel , linux-sound@vger.kernel.org X-Mailman-Version: 3.3.8 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: > > This is what I found after Googling a bit: > > Since you didn't specify a format, arecord defaults to 8 bit format (U8). > > Being unsigned, a negative value for maximum negative amplitude is impossible. Therefore the value is given a bias of 128, > > making 0 the maximum negative amplitude, 255 the maximum positive, and 128 the center point (or silence). > Thanks for the clarification. > So I tried passing signed 8-bit format (S8), and then the arecord died > immediately, as mentioned below. > > $ arecord -f S8 test.wav > Recording WAVE 'test.wav' : Signed 8 bit, Rate 8000 Hz, Mono > arecord: begin_wave:2481: Wave doesn't support S8 format... > > For other format S16_LE, the arecord hangs for a few seconds and > throws an I/O error. > > $ arecord -f S16_LE test.wav > Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 8000 Hz, Mono > arecord: pcm_read:2032: read error: Input/output error > > I am not sure why recording works only on the default format of U8. > For other formats, the record either dies immediately or hangs for a > timeout and then throws an I/O error. Any ideas about this behaviour? The flag --dump-hw-params should show the formats arecord supports On your installation. On top of that .wav does not support any big endian formats as well as no signed formats below 9 bit. You could try testing with raw file type instead. The i/o error *might* relate to incorrect device selection. I hope you can pinpoint your issue to something more specific - and provide more information - so people with actual expertise in this driver can help you, I just googled a bit to not leave your questions hovering around unanswered. Maybe take a peek into the guide on how to ask good questions, linked on the kernelnewbies site, to make your questions more concise and worth busy people's time. Best regards, Luke