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Paul Walmsley authored
When digitizing composite video from a analog videotape source using the TVP5150's first composite input channel, the captured stream exhibits tearing and synchronization problems[1]. It turns out that commit c0477ad9 caused "TV mode" (as opposed to "VCR mode" or "auto-detect") to be forcibly enabled for both composite inputs. According to the chip documentation[2], "TV mode" disables a "chrominance trap" input filter, which appears to be necessary for high-quality video capture from an analog videotape source. [ Commit c7c0b34c subsequently restricted the problem to the first composite input, apparently inadvertently. ] Since any type of composite signal source can be connected to the TVP5150's first composite input, unconditionally forcing "TV mode" isn't correct. There doesn't appear to be a good way for applications to tell the driver what is connected. Fortunately, the TVP5150 has an operating mode auto-detection feature, which, when enabled, should cause the TVP5150 to auto-detect whether it should use "VCR mode" or "TV mode". Enabling operating mode auto-detection improved video capture quality significantly[3]. Therefore, fix this bug by using operating mode auto-detection. (Also, while here, fix a CodingStyle issue.) For those users who may find this patch via a mailing list archive but who are not able to upgrade to a kernel with a fixed driver: the TVP5150's S-Video and second composite input sources have auto-detection enabled, so you may wish to try using those -- if available on your device -- until this fix makes it a downstream distribution near you. 1. Pre-patch tvtime snapshot using a Pinnacle PCTV HD Pro as the capture device and a Sony EV-S2000 as a video source: http://www.booyaka.com/~paul/tvp5150/1a.png 2. Section 3.21.3, "Operation Mode Control Register", _TVP5150AM1 Ultralow-Power NTSC/PAL/SECAM Video Decoder (Rev. D)_ [SLES209D], downloaded 8 October 2010, available via http://focus.ti.com/lit/ds/symlink/tvp5150am1.pdf 3. Post-patch tvtime snapshot (same signal chain as #1, above): http://www.booyaka.com/~paul/tvp5150/1b.pngSigned-off-by: Paul Walmsley <paul@booyaka.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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