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  • Le plugin : Podcasts.

    14 juillet 2010, par

    Le problème du podcasting est à nouveau un problème révélateur de la normalisation des transports de données sur Internet.
    Deux formats intéressants existent : Celui développé par Apple, très axé sur l’utilisation d’iTunes dont la SPEC est ici ; Le format "Media RSS Module" qui est plus "libre" notamment soutenu par Yahoo et le logiciel Miro ;
    Types de fichiers supportés dans les flux
    Le format d’Apple n’autorise que les formats suivants dans ses flux : .mp3 audio/mpeg .m4a audio/x-m4a .mp4 (...)

  • Encoding and processing into web-friendly formats

    13 avril 2011, par

    MediaSPIP automatically converts uploaded files to internet-compatible formats.
    Video files are encoded in MP4, Ogv and WebM (supported by HTML5) and MP4 (supported by Flash).
    Audio files are encoded in MP3 and Ogg (supported by HTML5) and MP3 (supported by Flash).
    Where possible, text is analyzed in order to retrieve the data needed for search engine detection, and then exported as a series of image files.
    All uploaded files are stored online in their original format, so you can (...)

  • Les images

    15 mai 2013

Sur d’autres sites (7388)

  • FFmpeg - MJPEG decoding gives inconsistent values

    28 décembre 2016, par ahmadh

    I have a set of JPEG frames which I am muxing into an avi, which gives me a mjpeg video. This is the command I run on the console :

    ffmpeg -y -start_number 0 -i %06d.JPEG -codec copy vid.avi

    When I try to demux the video using ffmpeg C api, I get frames which are slightly different in values. Demuxing code looks something like this :

    AVFormatContext* fmt_ctx = NULL;
    AVCodecContext* cdc_ctx = NULL;
    AVCodec* vid_cdc = NULL;
    int ret;
    unsigned int height, width;

    ....
    // read_nframes is the number of frames to read
    output_arr = new unsigned char [height * width * 3 *
                                   sizeof(unsigned char) * read_nframes];

    avcodec_open2(cdc_ctx, vid_cdc, NULL);

    int num_bytes;
    uint8_t* buffer = NULL;
    const AVPixelFormat out_format = AV_PIX_FMT_RGB24;

    num_bytes = av_image_get_buffer_size(out_format, width, height, 1);
    buffer = (uint8_t*)av_malloc(num_bytes * sizeof(uint8_t));

    AVFrame* vid_frame = NULL;
    vid_frame = av_frame_alloc();
    AVFrame* conv_frame = NULL;
    conv_frame = av_frame_alloc();

    av_image_fill_arrays(conv_frame->data, conv_frame->linesize, buffer,
                        out_format, width, height, 1);

    struct SwsContext *sws_ctx = NULL;
    sws_ctx = sws_getContext(width, height, cdc_ctx->pix_fmt,
                            width, height, out_format,
                            SWS_BILINEAR, NULL,NULL,NULL);

    int frame_num = 0;
    AVPacket vid_pckt;
    while (av_read_frame(fmt_ctx, &vid_pckt) >=0) {
       ret = avcodec_send_packet(cdc_ctx, &vid_pckt);
       if (ret < 0)
           break;

       ret = avcodec_receive_frame(cdc_ctx, vid_frame);
       if (ret < 0 && ret != AVERROR(EAGAIN) && ret != AVERROR_EOF)
           break;
       if (ret >= 0) {
           // convert image from native format to planar GBR
           sws_scale(sws_ctx, vid_frame->data,
                     vid_frame->linesize, 0, vid_frame->height,
                     conv_frame->data, conv_frame->linesize);

           unsigned char* r_ptr = output_arr +
               (height * width * sizeof(unsigned char) * 3 * frame_num);
           unsigned char* g_ptr = r_ptr + (height * width * sizeof(unsigned char));
           unsigned char* b_ptr = g_ptr + (height * width * sizeof(unsigned char));
           unsigned int pxl_i = 0;

           for (unsigned int r = 0; r < height; ++r) {
               uint8_t* avframe_r = conv_frame->data[0] + r*conv_frame->linesize[0];
               for (unsigned int c = 0; c < width; ++c) {
                   r_ptr[pxl_i] = avframe_r[0];
                   g_ptr[pxl_i]   = avframe_r[1];
                   b_ptr[pxl_i]   = avframe_r[2];
                   avframe_r += 3;
                   ++pxl_i;
               }
           }

           ++frame_num;

           if (frame_num >= read_nframes)
               break;
       }
    }

    ...

    In my experience around two-thirds of the pixel values are different, each by +-1 (in a range of [0,255]). I am wondering is it due to some decoding scheme FFmpeg uses for reading JPEG frames ? I tried encoding and decoding png frames, and it works perfectly fine. I am sure this is something to do with the libav decoding process because the MD5 values are consistent between the images and the video :

    ffmpeg -i %06d.JPEG -f framemd5 -
    ffmpeg -i vid.avi -f framemd5 -

    In short my goal is to get the same pixel by pixel values for each JPEG frame as I would I have gotten if I was reading the JPEG images directly. Here is the stand-alone bitbucket code I used. It includes cmake files to build code, and a couple of jpeg frames with the converted avi file to test this problem. (give ’—filetype png’ to test the png decoding).

  • How to using every 5 sec generate video output File Path to Encode with RTMP Formate write data in ios ? [on hold]

    16 juillet 2015, par Sandeep Joshi
    (void) segmentRecording:(NSTimer*)timer {
    if (!shouldBeRecording) {
       [timer invalidate];
    }
    AVAssetWriter *tempAssetWriter = self.assetWriter;
    AVAssetWriterInput *tempAudioEncoder = self.audioEncoder;
    AVAssetWriterInput *tempVideoEncoder = self.videoEncoder;
    self.assetWriter = queuedAssetWriter;
    self.audioEncoder = queuedAudioEncoder;
    self.videoEncoder = queuedVideoEncoder;
    NSLog(@"Switching encoders");

    dispatch_async(segmentingQueue, ^{
       if (tempAssetWriter.status == AVAssetWriterStatusWriting) {
           @try {
               [tempAudioEncoder markAsFinished];
               [tempVideoEncoder markAsFinished];
               [tempAssetWriter finishWritingWithCompletionHandler:^{
                   if (tempAssetWriter.status == AVAssetWriterStatusFailed) {
                       [self showError:tempAssetWriter.error];
                   } else {
                       [self uploadLocalURL:tempAssetWriter.outputURL];
                   }
               }];
           }
           @catch (NSException *exception) {
               NSLog(@"Caught exception: %@", [exception description]);
               //[BugSenseController logException:exception withExtraData:nil];
           }
       }
       self.segmentCount++;
       if (self.readyToRecordAudio && self.readyToRecordVideo) {
           NSError *error = nil;
           self.queuedAssetWriter = [[AVAssetWriter alloc] initWithURL:[OWUtilities urlForRecordingSegmentCount:segmentCount basePath:self.basePath] fileType:(NSString *)kUTTypeMPEG4 error:&error];
           if (error) {
               [self showError:error];
           }
           self.queuedVideoEncoder = [self setupVideoEncoderWithAssetWriter:self.queuedAssetWriter formatDescription:videoFormatDescription bitsPerSecond:videoBPS];
           self.queuedAudioEncoder = [self setupAudioEncoderWithAssetWriter:self.queuedAssetWriter formatDescription:audioFormatDescription bitsPerSecond:audioBPS];
           //NSLog(@"Encoder switch finished");
       }
    });}



    (void) uploadLocalURL:(NSURL*)url {
    NSLog(@"upload local url: %@", url);
    NSString *inputPath = [url path];
    NSString *outputPath = [inputPath stringByReplacingOccurrencesOfString:@".mp4" withString:@".ts"];
    NSString *outputFileName = [outputPath lastPathComponent];
    NSDictionary *options = @{kFFmpegOutputFormatKey: @"mpegts"};
    NSLog(@"%@ conversion...", outputFileName);
    [ffmpegWrapper convertInputPath:[url path] outputPath:outputPath options:options progressBlock:nil completionBlock:^(BOOL success, NSError *error) {
       if (success) {
           if (!isRtmpConnected) {
               isRtmpConnected = [rtmp openWithURL:HOST_URL enableWrite:YES];
           }
           isRtmpConnected = [rtmp isConnected];

           if (isRtmpConnected) {

               NSData *video = [NSData dataWithContentsOfURL:[NSURL URLWithString:outputPath]];
               NSUInteger length = [video length];
               NSUInteger chunkSize = 1024 * 5;;
               NSUInteger offset = 0;
               NSLog(@"original video length: %lu \n chunkSize : %lu", length,chunkSize);
             // Let's split video to small chunks to publish to media server
               do {
                   NSUInteger thisChunkSize = length - offset > chunkSize ? chunkSize : length - offset;
                   NSData* chunk = [NSData dataWithBytesNoCopy:(char *)[video bytes] + offset
                                                        length:thisChunkSize
                                                  freeWhenDone:NO];
                   offset += thisChunkSize;

                   // Write new chunk to rtmp server
                   NSLog(@"%lu", (unsigned long)[rtmp write:chunk]);
                   sleep(1);
               } while (offset < length);
           }else{
               [rtmp close];
           }


       } else {
           NSLog(@"conversion error: %@", error.userInfo);
       }
    }];}

    This code use for live streaming for send data using RTMP Wrapper.
    Not write in Socket properly because every 5 second to generate different file output file.

    This is proper way ?

    I have no idea how to get NSData in proper way.

    Please help me .

  • Compiling ffmpeg for iOS and gas-preprocessor.pl

    16 mai 2017, par user500

    I want to compile ffmpeg for iOS. I did it a few times before. But now I’m on clean new Mavericks and on configure I’m always getting

    Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
    Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
    GNU assembler not found, install gas-preprocessor

    If you think configure made a mistake, make sure you are using the latest
    version from Git.  If the latest version fails, report the problem to the
    ffmpeg-user@ffmpeg.org mailing list or IRC #ffmpeg on irc.freenode.net.
    Include the log file "config.log" produced by configure as this will help
    solving the problem.

    I have current Xcode installed. Also brews. And current gas-preprocessor.pl (https://github.com/yuvi/gas-preprocessor) in usr/bin and also in usr/local/bin.


    On perl /usr/bin/gas-preprocessor.pl gcc I’m getting Unrecognized input filetype at /usr/bin/gas-preprocessor.pl line 33.


    This config works :

    ./configure \
    --extra-cflags='-arch arm64 -mios-version-min=7.0 -mthumb' \
    --extra-ldflags='-arch arm64 -mios-version-min=7.0' \
    --enable-cross-compile \
    --arch=arm64 \
    --target-os=darwin \
    --cc=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang \
    --sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk \
    --prefix=arm64 \
    --disable-doc \
    --disable-shared \
    --disable-everything \
    --enable-static \
    --enable-pic \
    --disable-muxers \
    --enable-muxer=flv \
    --disable-demuxers \
    --enable-demuxer=h264 \
    --enable-demuxer=pcm_s16le \
    --disable-devices \
    --disable-parsers \
    --enable-parser=h264 \
    --disable-encoders \
    --enable-encoder=aac \
    --disable-decoders \
    --enable-decoder=h264 \
    --enable-decoder=pcm_s16le \
    --disable-protocols \
    --enable-protocol=rtmp \
    --disable-filters \
    --disable-bsfs

    This config throws error above (GNU assembler not found, install gas-preprocessor) :

    ./configure \
    --cpu=cortex-a8 \
    --extra-cflags='-arch armv7 -mios-version-min=7.0 -mthumb' \
    --extra-ldflags='-arch armv7 -mios-version-min=7.0' \
    --enable-cross-compile \
    --arch=armv7 \
    --target-os=darwin \
    --cc=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang \
    --sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk \
    --prefix=armv7 \
    --disable-doc \
    --disable-shared \
    --disable-everything \
    --enable-static \
    --enable-pic \
    --disable-muxers \
    --enable-muxer=flv \
    --disable-demuxers \
    --enable-demuxer=h264 \
    --enable-demuxer=pcm_s16le \
    --disable-devices \
    --disable-parsers \
    --enable-parser=h264 \
    --disable-encoders \
    --enable-encoder=aac \
    --disable-decoders \
    --enable-decoder=h264 \
    --enable-decoder=pcm_s16le \
    --disable-protocols \
    --enable-protocol=rtmp \
    --disable-filters \
    --disable-bsfs