diff --git a/CHANGELOG.md b/CHANGELOG.md --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -1,3 +1,6 @@ +# 0.13.0 +* Support webcams on Linux + # 0.12.2.2 * Fix a video playback framerate issue in the `vplay` demo (@gelisam) diff --git a/demo/Main.hs b/demo/Main.hs --- a/demo/Main.hs +++ b/demo/Main.hs @@ -5,6 +5,7 @@ import qualified Data.Time.Clock as C import qualified Data.Vector.Storable as V import System.Environment +import qualified System.Info as Info import Control.Monad (unless) -- The example used in the README @@ -65,11 +66,20 @@ unless (realToFrac (C.diffUTCTime now start) >= time) go go -testCamera :: IO () -testCamera = +testCamera :: String -> IO () +testCamera cameraDevice = do initFFmpeg -- Defaults to quiet (minimal) logging -- setLogLevel avLogInfo -- Restore standard ffmpeg logging - (getFrame, cleanup) <- imageReader (Camera "0:0" defaultCameraConfig) + putStrLn "Opening camera..." + (getFrame, cleanup) <- imageReader $ + case Info.os of + "linux" -> + let cfg = CameraConfig (Just 30) Nothing (Just "mjpeg") + -- (Just "v4l2") + in Camera ("/dev/video" <> cameraDevice) cfg + "darwin" -> Camera "0:0" defaultCameraConfig + _ -> error "Unsure how to identify a default camera input" + frame1 <- getFrame case frame1 of img@(Just (Image w h _)) -> @@ -86,15 +96,23 @@ main = do args <- getArgs case args of [] -> testEncode + ["cam", n] -> testCamera n [s] - | s `elem` ["--help", "-help", "-h"] -> error usage - | s == "cam" -> testCamera + | s `elem` ["--help", "-help", "-h"] -> putStrLn usage + | s == "cam" -> testCamera "0" [vidFile] -> testDecode vidFile _ -> error usage where usage = - unlines [ "Usage: demo [videoFile]" + unlines [ "Usage: demo [cam [N]|videoFile]" , " If no argument is given, a test video named " , " pulse.mov is generated." + , "" + , " If the word 'cam' (without quotes) is given as an " + , " argument, an attached webcam is opened and used to " + , " record a 10s video saved to the file camera.mov. " + , " On Linux, the camera is found at /dev/videoN where N " + , " is an argument following the word 'cam'. If no value " + , " is given for N, a default of 0 is used." , "" , " If a file name is given, then two frames are " , " extracted: the first frame, and the 301st." diff --git a/demo/VPlay.hs b/demo/VPlay.hs --- a/demo/VPlay.hs +++ b/demo/VPlay.hs @@ -266,13 +266,24 @@ (vsIdx, ctx, _, vs, _) <- prepareVideoCodec inputContext -- Get frame size. - w <- liftIO $ getWidth ctx - h <- liftIO $ getHeight ctx + textureWidth <- liftIO $ getWidth ctx + textureHeight <- liftIO $ getHeight ctx + -- Compute window size. If the pixels aren't square, stretch the window, + -- SDL will automatically scale the texture to fit. + par <- liftIO $ guessAspectRatio ctx + + let pixelAspectRatio :: Double + pixelAspectRatio = fromIntegral (numerator par) / fromIntegral (denomenator par) + + windowWidth, windowHeight :: CInt + windowWidth = round (pixelAspectRatio * fromIntegral textureWidth) + windowHeight = textureHeight + -- Create window, renderer and texture. - window <- createWindow w h + window <- createWindow windowWidth windowHeight renderer <- createRenderer window - texture <- createTexture renderer w h + texture <- createTexture renderer textureWidth textureHeight -- Create frame reader. let dstFmt = cfgFmtFFmpeg cfg diff --git a/ffmpeg-light.cabal b/ffmpeg-light.cabal --- a/ffmpeg-light.cabal +++ b/ffmpeg-light.cabal @@ -1,5 +1,5 @@ name: ffmpeg-light -version: 0.12.2.2 +version: 0.13.0 synopsis: Minimal bindings to the FFmpeg library. description: Stream frames from an encoded video, or stream frames to @@ -15,7 +15,7 @@ > go = do (getFrame, cleanup) <- imageReader "myVideo.mov" > (fmap ImageRGB8 <$> getFrame) <* cleanup . - Tested with FFmpeg 3.1 - 3.4.2 + Tested with FFmpeg 3.1 - 4.3.1 license: BSD3 license-file: LICENSE @@ -28,7 +28,7 @@ build-type: Simple extra-source-files: src/hscMacros.h, src/nameCompat.h, CHANGELOG.md cabal-version: >=1.10 -tested-with: GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.2 +tested-with: GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.2, GHC == 8.6.5, GHC == 8.8.4 source-repository head type: git @@ -67,7 +67,7 @@ Codec.FFmpeg.Internal.Debug, Codec.FFmpeg.Internal.Linear build-tools: hsc2hs - build-depends: base >=4.6 && < 4.12, + build-depends: base >=4.6 && < 5, either, exceptions, vector >= 0.10.9 && < 0.13, diff --git a/src/Codec/FFmpeg/Decode.hs b/src/Codec/FFmpeg/Decode.hs --- a/src/Codec/FFmpeg/Decode.hs +++ b/src/Codec/FFmpeg/Decode.hs @@ -22,7 +22,7 @@ -- * FFI Declarations foreign import ccall "avformat_open_input" - avformat_open_input :: Ptr AVFormatContext -> CString -> Ptr () + avformat_open_input :: Ptr AVFormatContext -> CString -> Ptr AVInputFormat -> Ptr AVDictionary -> IO CInt foreign import ccall "avformat_find_stream_info" @@ -56,6 +56,12 @@ foreign import ccall "av_dict_set" av_dict_set :: Ptr AVDictionary -> CString -> CString -> CInt -> IO CInt +foreign import ccall "av_find_input_format" + av_find_input_format :: CString -> IO (Ptr AVInputFormat) + +foreign import ccall "av_format_set_video_codec" + av_format_set_video_codec :: AVFormatContext -> AVCodec -> IO () + dictSet :: Ptr AVDictionary -> String -> String -> IO () dictSet d k v = do r <- withCString k $ \k' -> withCString v $ \v' -> @@ -74,9 +80,13 @@ do avPtr <- mallocAVFormatContext setupCamera avPtr cam poke ctx avPtr + fmt <- case format cfg of + Just "mjpeg" -> withCString "v4l2" av_find_input_format + Just f -> withCString f av_find_input_format + Nothing -> pure nullPtr r <- alloca $ \dict -> do setConfig dict cfg - avformat_open_input ctx cstr nullPtr dict + avformat_open_input ctx cstr fmt dict when (r /= 0) $ stringError r >>= \err -> fail ("ffmpeg failed opening file: " ++ err) @@ -95,6 +105,10 @@ setupCamera avfc c = do setCamera avfc setFilename avfc c + when (format cfg == Just "mjpeg") $ do + mjpeg <- avcodec_find_decoder avCodecIdMjpeg + setVideoCodecID avfc avCodecIdMjpeg + av_format_set_video_codec avfc mjpeg openInput :: (MonadIO m, MonadError String m) => InputSource -> m AVFormatContext openInput ipt = diff --git a/src/Codec/FFmpeg/Enums.hsc b/src/Codec/FFmpeg/Enums.hsc --- a/src/Codec/FFmpeg/Enums.hsc +++ b/src/Codec/FFmpeg/Enums.hsc @@ -10,6 +10,7 @@ #include #include #include +#include #include "nameCompat.h" newtype AVMediaType = AVMediaType CInt deriving (Eq, Storable) @@ -68,18 +69,266 @@ newtype AVCodecID = AVCodecID CInt deriving (Eq, Show, Storable) #enum AVCodecID,AVCodecID \ + , AV_CODEC_ID_NONE\ + , AV_CODEC_ID_MPEG1VIDEO\ + , AV_CODEC_ID_MPEG2VIDEO\ + , AV_CODEC_ID_H261\ + , AV_CODEC_ID_H263\ + , AV_CODEC_ID_RV10\ + , AV_CODEC_ID_RV20\ + , AV_CODEC_ID_MJPEG\ + , AV_CODEC_ID_MJPEGB\ + , AV_CODEC_ID_LJPEG\ + , AV_CODEC_ID_SP5X\ + , AV_CODEC_ID_JPEGLS\ + , AV_CODEC_ID_MPEG4\ + , AV_CODEC_ID_RAWVIDEO\ + , AV_CODEC_ID_MSMPEG4V1\ + , AV_CODEC_ID_MSMPEG4V2\ + , AV_CODEC_ID_MSMPEG4V3\ + , AV_CODEC_ID_WMV1\ + , AV_CODEC_ID_WMV2\ + , AV_CODEC_ID_H263P\ + , AV_CODEC_ID_H263I\ + , AV_CODEC_ID_FLV1\ + , AV_CODEC_ID_SVQ1\ + , AV_CODEC_ID_SVQ3\ + , AV_CODEC_ID_DVVIDEO\ + , AV_CODEC_ID_HUFFYUV\ + , AV_CODEC_ID_CYUV\ , AV_CODEC_ID_H264\ - , AV_CODEC_ID_HEVC\ + , AV_CODEC_ID_INDEO3\ + , AV_CODEC_ID_VP3\ , AV_CODEC_ID_THEORA\ + , AV_CODEC_ID_ASV1\ + , AV_CODEC_ID_ASV2\ + , AV_CODEC_ID_FFV1\ + , AV_CODEC_ID_4XM\ + , AV_CODEC_ID_VCR1\ + , AV_CODEC_ID_CLJR\ + , AV_CODEC_ID_MDEC\ + , AV_CODEC_ID_ROQ\ + , AV_CODEC_ID_INTERPLAY_VIDEO\ + , AV_CODEC_ID_XAN_WC3\ + , AV_CODEC_ID_XAN_WC4\ + , AV_CODEC_ID_RPZA\ + , AV_CODEC_ID_CINEPAK\ + , AV_CODEC_ID_WS_VQA\ + , AV_CODEC_ID_MSRLE\ + , AV_CODEC_ID_MSVIDEO1\ + , AV_CODEC_ID_IDCIN\ + , AV_CODEC_ID_8BPS\ + , AV_CODEC_ID_SMC\ + , AV_CODEC_ID_FLIC\ + , AV_CODEC_ID_TRUEMOTION1\ + , AV_CODEC_ID_VMDVIDEO\ + , AV_CODEC_ID_MSZH\ + , AV_CODEC_ID_ZLIB\ + , AV_CODEC_ID_QTRLE\ + , AV_CODEC_ID_TSCC\ + , AV_CODEC_ID_ULTI\ + , AV_CODEC_ID_QDRAW\ + , AV_CODEC_ID_VIXL\ + , AV_CODEC_ID_QPEG\ + , AV_CODEC_ID_PNG\ + , AV_CODEC_ID_PPM\ + , AV_CODEC_ID_PBM\ + , AV_CODEC_ID_PGM\ + , AV_CODEC_ID_PGMYUV\ + , AV_CODEC_ID_PAM\ + , AV_CODEC_ID_FFVHUFF\ + , AV_CODEC_ID_RV30\ + , AV_CODEC_ID_RV40\ , AV_CODEC_ID_VC1\ - , AV_CODEC_ID_MPEG4\ - , AV_CODEC_ID_MPEG2VIDEO\ - , AV_CODEC_ID_RAWVIDEO\ + , AV_CODEC_ID_WMV3\ + , AV_CODEC_ID_LOCO\ + , AV_CODEC_ID_WNV1\ + , AV_CODEC_ID_AASC\ + , AV_CODEC_ID_INDEO2\ + , AV_CODEC_ID_FRAPS\ + , AV_CODEC_ID_TRUEMOTION2\ + , AV_CODEC_ID_BMP\ + , AV_CODEC_ID_CSCD\ + , AV_CODEC_ID_MMVIDEO\ + , AV_CODEC_ID_ZMBV\ + , AV_CODEC_ID_AVS\ + , AV_CODEC_ID_SMACKVIDEO\ + , AV_CODEC_ID_NUV\ + , AV_CODEC_ID_KMVC\ + , AV_CODEC_ID_FLASHSV\ + , AV_CODEC_ID_CAVS\ + , AV_CODEC_ID_JPEG2000\ + , AV_CODEC_ID_VMNC\ + , AV_CODEC_ID_VP5\ + , AV_CODEC_ID_VP6\ + , AV_CODEC_ID_VP6F\ + , AV_CODEC_ID_TARGA\ + , AV_CODEC_ID_DSICINVIDEO\ + , AV_CODEC_ID_TIERTEXSEQVIDEO\ + , AV_CODEC_ID_TIFF\ , AV_CODEC_ID_GIF\ - , AV_CODEC_ID_AAC\ + , AV_CODEC_ID_DXA\ + , AV_CODEC_ID_DNXHD\ + , AV_CODEC_ID_THP\ + , AV_CODEC_ID_SGI\ + , AV_CODEC_ID_C93\ + , AV_CODEC_ID_BETHSOFTVID\ + , AV_CODEC_ID_PTX\ + , AV_CODEC_ID_TXD\ + , AV_CODEC_ID_VP6A\ + , AV_CODEC_ID_AMV\ + , AV_CODEC_ID_VB\ + , AV_CODEC_ID_PCX\ + , AV_CODEC_ID_SUNRAST\ + , AV_CODEC_ID_INDEO4\ + , AV_CODEC_ID_INDEO5\ + , AV_CODEC_ID_MIMIC\ + , AV_CODEC_ID_RL2\ + , AV_CODEC_ID_ESCAPE124\ + , AV_CODEC_ID_DIRAC\ + , AV_CODEC_ID_BFI\ + , AV_CODEC_ID_CMV\ + , AV_CODEC_ID_MOTIONPIXELS\ + , AV_CODEC_ID_TGV\ + , AV_CODEC_ID_TGQ\ + , AV_CODEC_ID_TQI\ + , AV_CODEC_ID_AURA\ + , AV_CODEC_ID_AURA2\ + , AV_CODEC_ID_V210X\ + , AV_CODEC_ID_TMV\ + , AV_CODEC_ID_V210\ + , AV_CODEC_ID_DPX\ + , AV_CODEC_ID_MAD\ + , AV_CODEC_ID_FRWU\ + , AV_CODEC_ID_FLASHSV2\ + , AV_CODEC_ID_CDGRAPHICS\ + , AV_CODEC_ID_R210\ + , AV_CODEC_ID_ANM\ + , AV_CODEC_ID_BINKVIDEO\ + , AV_CODEC_ID_IFF_ILBM\ + , AV_CODEC_ID_KGV1\ + , AV_CODEC_ID_YOP\ + , AV_CODEC_ID_VP8\ + , AV_CODEC_ID_PICTOR\ + , AV_CODEC_ID_ANSI\ + , AV_CODEC_ID_A64_MULTI\ + , AV_CODEC_ID_A64_MULTI5\ + , AV_CODEC_ID_R10K\ + , AV_CODEC_ID_MXPEG\ + , AV_CODEC_ID_LAGARITH\ + , AV_CODEC_ID_PRORES\ + , AV_CODEC_ID_JV\ + , AV_CODEC_ID_DFA\ + , AV_CODEC_ID_WMV3IMAGE\ + , AV_CODEC_ID_VC1IMAGE\ + , AV_CODEC_ID_UTVIDEO\ + , AV_CODEC_ID_BMV_VIDEO\ + , AV_CODEC_ID_VBLE\ + , AV_CODEC_ID_DXTORY\ + , AV_CODEC_ID_V410\ + , AV_CODEC_ID_XWD\ + , AV_CODEC_ID_CDXL\ + , AV_CODEC_ID_XBM\ + , AV_CODEC_ID_ZEROCODEC\ + , AV_CODEC_ID_MSS1\ + , AV_CODEC_ID_MSA1\ + , AV_CODEC_ID_TSCC2\ + , AV_CODEC_ID_MTS2\ + , AV_CODEC_ID_CLLC\ + , AV_CODEC_ID_MSS2\ + , AV_CODEC_ID_VP9\ + , AV_CODEC_ID_AIC\ + , AV_CODEC_ID_ESCAPE130\ + , AV_CODEC_ID_G2M\ + , AV_CODEC_ID_WEBP\ + , AV_CODEC_ID_HNM4_VIDEO\ + , AV_CODEC_ID_HEVC\ + , AV_CODEC_ID_MP2\ , AV_CODEC_ID_MP3\ - , AV_CODEC_ID_DTS + , AV_CODEC_ID_AAC\ + , AV_CODEC_ID_AC3\ + , AV_CODEC_ID_DTS\ + , AV_CODEC_ID_VORBIS\ + , AV_CODEC_ID_DVAUDIO\ + , AV_CODEC_ID_WMAV1\ + , AV_CODEC_ID_WMAV2\ + , AV_CODEC_ID_MACE3\ + , AV_CODEC_ID_MACE6\ + , AV_CODEC_ID_VMDAUDIO\ + , AV_CODEC_ID_FLAC\ + , AV_CODEC_ID_MP3ADU\ + , AV_CODEC_ID_MP3ON4\ + , AV_CODEC_ID_SHORTEN\ + , AV_CODEC_ID_ALAC\ + , AV_CODEC_ID_WESTWOOD_SND1\ + , AV_CODEC_ID_GSM\ + , AV_CODEC_ID_QDM2\ + , AV_CODEC_ID_COOK\ + , AV_CODEC_ID_TRUESPEECH\ + , AV_CODEC_ID_TTA\ + , AV_CODEC_ID_SMACKAUDIO\ + , AV_CODEC_ID_QCELP\ + , AV_CODEC_ID_WAVPACK\ + , AV_CODEC_ID_DSICINAUDIO\ + , AV_CODEC_ID_IMC\ + , AV_CODEC_ID_MUSEPACK7\ + , AV_CODEC_ID_MLP\ + , AV_CODEC_ID_GSM_MS\ + , AV_CODEC_ID_ATRAC3\ + , AV_CODEC_ID_APE\ + , AV_CODEC_ID_NELLYMOSER\ + , AV_CODEC_ID_MUSEPACK8\ + , AV_CODEC_ID_SPEEX\ + , AV_CODEC_ID_WMAVOICE\ + , AV_CODEC_ID_WMAPRO\ + , AV_CODEC_ID_WMALOSSLESS\ + , AV_CODEC_ID_ATRAC3P\ + , AV_CODEC_ID_EAC3\ + , AV_CODEC_ID_SIPR\ + , AV_CODEC_ID_MP1\ + , AV_CODEC_ID_TWINVQ\ + , AV_CODEC_ID_TRUEHD\ + , AV_CODEC_ID_MP4ALS\ + , AV_CODEC_ID_ATRAC1\ + , AV_CODEC_ID_BINKAUDIO_RDFT\ + , AV_CODEC_ID_BINKAUDIO_DCT\ + , AV_CODEC_ID_AAC_LATM\ + , AV_CODEC_ID_QDMC\ + , AV_CODEC_ID_CELT\ + , AV_CODEC_ID_G723_1\ + , AV_CODEC_ID_G729\ + , AV_CODEC_ID_8SVX_EXP\ + , AV_CODEC_ID_8SVX_FIB\ + , AV_CODEC_ID_BMV_AUDIO\ + , AV_CODEC_ID_RALF\ + , AV_CODEC_ID_IAC\ + , AV_CODEC_ID_ILBC\ + , AV_CODEC_ID_OPUS\ + , AV_CODEC_ID_COMFORT_NOISE\ + , AV_CODEC_ID_TAK\ + , AV_CODEC_ID_METASOUND\ + , AV_CODEC_ID_PAF_AUDIO\ + , AV_CODEC_ID_ON2AVC\ + , AV_CODEC_ID_DSS_SP\ + , AV_CODEC_ID_FFWAVESYNTH\ + , AV_CODEC_ID_SONIC\ + , AV_CODEC_ID_SONIC_LS\ + , AV_CODEC_ID_EVRC\ + , AV_CODEC_ID_SMV\ + , AV_CODEC_ID_DSD_LSBF\ + , AV_CODEC_ID_DSD_MSBF\ + , AV_CODEC_ID_DSD_LSBF_PLANAR\ + , AV_CODEC_ID_DSD_MSBF_PLANAR\ + , AV_CODEC_ID_4GV + + -- \ + -- , AV_CODEC_ID_INTERPLAY_ACM\ + -- , AV_CODEC_ID_XMA1\ + -- , AV_CODEC_ID_XMA2\ + -- , AV_CODEC_ID_DST + + newtype SwsAlgorithm = SwsAlgorithm CUInt deriving (Eq, Show, Storable) #enum SwsAlgorithm,SwsAlgorithm \ , SWS_FAST_BILINEAR\ @@ -266,3 +515,21 @@ , AV_LOG_DEBUG\ , AV_LOG_TRACE\ , AV_LOG_MAX_OFFSET + +newtype AVSampleFormat = AVSampleFormat CInt deriving (Eq, Bits, Storable) +#enum AVSampleFormat, AVSampleFormat \ + , AV_SAMPLE_FMT_NONE\ + , AV_SAMPLE_FMT_U8\ + , AV_SAMPLE_FMT_S16\ + , AV_SAMPLE_FMT_S32\ + , AV_SAMPLE_FMT_FLT\ + , AV_SAMPLE_FMT_DBL\ + , AV_SAMPLE_FMT_U8P\ + , AV_SAMPLE_FMT_S16P\ + , AV_SAMPLE_FMT_S32P\ + , AV_SAMPLE_FMT_FLTP\ + , AV_SAMPLE_FMT_DBLP\ + , AV_SAMPLE_FMT_NB + +getSampleFormatInt :: AVSampleFormat -> CInt +getSampleFormatInt (AVSampleFormat i) = i diff --git a/src/Codec/FFmpeg/Types.hsc b/src/Codec/FFmpeg/Types.hsc --- a/src/Codec/FFmpeg/Types.hsc +++ b/src/Codec/FFmpeg/Types.hsc @@ -3,6 +3,7 @@ module Codec.FFmpeg.Types where import Codec.FFmpeg.Enums import Control.Monad (zipWithM_,when) +import Data.Maybe (fromMaybe) import Foreign.C.String (CString) import Foreign.C.Types import Foreign.Ptr @@ -32,6 +33,7 @@ #hasField AVFormatContext, OutputFormat, oformat #hasField AVFormatContext, InputFormat, iformat #hasField AVFormatContext, IOContext, pb +#hasField AVFormatContext, VideoCodecID, video_codec_id setFilename :: AVFormatContext -> String -> IO () setFilename ctx fn = @@ -77,6 +79,8 @@ #mkField CodecFlags, CodecFlag #mkField CodecID, AVCodecID #mkField PrivData, (Ptr ()) +#mkField TicksPerFrame, CInt +#mkField RawAspectRatio, AVRational #hasField AVCodecContext, Width, width #hasField AVCodecContext, Height, height @@ -86,7 +90,26 @@ #hasField AVCodecContext, CodecFlags, flags #hasField AVCodecContext, CodecID, codec_id #hasField AVCodecContext, PrivData, priv_data +#hasField AVCodecContext, TicksPerFrame, ticks_per_frame +#hasField AVCodecContext, RawAspectRatio, sample_aspect_ratio +getFps :: (HasTimeBase a, HasTicksPerFrame a) => a -> IO CDouble +getFps x = do + timeBase <- getTimeBase x + ticksPerFrame <- getTicksPerFrame x + pure (1.0 / av_q2d timeBase / fromIntegral ticksPerFrame) + +getAspectRatio :: HasRawAspectRatio a => a -> IO (Maybe AVRational) +getAspectRatio = fmap nonZeroAVRational . getRawAspectRatio + +-- | When unspecified, the most likely pixel shape is a square +guessAspectRatio :: HasRawAspectRatio a => a -> IO AVRational +guessAspectRatio = fmap (fromMaybe (AVRational 1 1)) . getAspectRatio + +setAspectRatio :: HasRawAspectRatio a => a -> Maybe AVRational -> IO () +setAspectRatio x Nothing = setRawAspectRatio x (AVRational 0 1) +setAspectRatio x (Just ratio) = setRawAspectRatio x ratio + newtype AVStream = AVStream (Ptr ()) deriving (Storable, HasPtr) #mkField Id, CInt @@ -182,6 +205,11 @@ data AVRational = AVRational { numerator :: CInt , denomenator :: CInt } deriving Show +-- | FFmpeg often uses 0 to mean "unknown"; use 'Nothing' instead. +nonZeroAVRational :: AVRational -> Maybe AVRational +nonZeroAVRational (AVRational 0 _) = Nothing +nonZeroAVRational ratio = Just ratio + instance Storable AVRational where sizeOf _ = #size AVRational alignment _ = #size AVRational @@ -228,8 +256,10 @@ data CameraConfig = CameraConfig { framerate :: Maybe Int , resolution :: Maybe (Int,Int) + , format :: Maybe String + -- ^ Short name for a video format (e.g. @"v4l2"@) } deriving (Eq,Ord,Show,Read) defaultCameraConfig :: CameraConfig -defaultCameraConfig = CameraConfig (Just 30) Nothing +defaultCameraConfig = CameraConfig (Just 30) Nothing Nothing