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• How to remove colour background into transparent or other colour with ffmpeg ?

  30 janvier 2017, par FillzZ

  My video is like in this picture. I need to remove blue background into transparent or other colour. How can I make it ?enter image description here

• How to download/convert multiple streams to multiple outputs with FFmpeg ?

  16 avril 2016, par Website Newbie

  Let’s say I have 20 different online stream videos (playlist.m3u8) and I want every video to output to their own .avi files. How can I do that in single file, so I don’t have to download and convert every single one separately ?

  I found a -map command online, but didn’t get straight answer to this.

  Will this be a working code ?

  ffmpeg -i 1playlist.m3u8 -vf scale=768:-1 -vcodec libx264 -crf 24 -acodec copy -map 0 1.avi \
  
  -i 2playlist.m3u8 -vf scale=768:-1 -vcodec libx264 -crf 24 -acodec copy -map 1 2.avi \
  
  -i 3playlist.m3u8 -vf scale=768:-1 -vcodec libx264 -crf 24 -acodec copy -map 2 3.avi

• How to seek one frame forward in ffmpeg [closed]

  10 mars, par Summit

  i want to seek one frame forward when i call this function but it gets stuck on the first frame seeked and does not move forward.

  


  void seekFrameUp() {
    if (!fmt_ctx || video_stream_index == -1) return;

    AVRational frame_rate = fmt_ctx->streams[video_stream_index]->r_frame_rate;
    if (frame_rate.num == 0) return;  // Avoid division by zero

    // Compute frame duration in AV_TIME_BASE_Q
    int64_t frame_duration = av_rescale_q(1,
        av_make_q(frame_rate.den, frame_rate.num),
        AV_TIME_BASE_Q);

    int64_t next_pts = requestedTimestamp + frame_duration;

    qDebug() << "Seeking forward: " << next_pts
        << " (Current PTS: " << requestedTimestamp
        << ", Frame Duration: " << frame_duration << ")";

    requestFrameAt(next_pts);

    // Update the requested timestamp after seeking
    requestedTimestamp = next_pts;
}





void requestFrameAt(int64_t timestamp) {
     {
         std::lock_guard lock(mtx);
         decoding = true;  // Ensure the thread keeps decoding when needed
     }
     cv.notify_one();
 }


void decodeLoop() {
    while (!stopThread) {
        std::unique_lock lock(mtx);
        cv.wait(lock, [this] { return decoding || stopThread; });

        if (stopThread) break;

        // Avoid redundant seeking
        if (requestedTimestamp == lastRequestedTimestamp) {
            decoding = false;
            continue;
        }

       

        lastRequestedTimestamp.store(requestedTimestamp.load());
        int64_t target_pts = av_rescale_q(requestedTimestamp, AV_TIME_BASE_Q, fmt_ctx->streams[video_stream_index]->time_base);

        target_pts = FFMAX(target_pts, 0); // Ensure it's not negative

        if (av_seek_frame(fmt_ctx, video_stream_index, target_pts, AVSEEK_FLAG_ANY) >= 0) {
            avcodec_flush_buffers(codec_ctx);  // Clear old frames from the decoder
            qDebug() << "Seek successful to PTS:" << target_pts;
        }
        else {
            qDebug() << "Seeking failed!";
            decoding = false;
            continue;
        }

        lock.unlock();

        // Keep decoding until we receive a valid frame
        bool frameDecoded = false;
        while (av_read_frame(fmt_ctx, pkt) >= 0) {
            if (pkt->stream_index == video_stream_index) {
                if (avcodec_send_packet(codec_ctx, pkt) == 0) {
                    while (avcodec_receive_frame(codec_ctx, frame) == 0) {
                        qDebug() << "FRAME DECODED ++++++++++++ PTS:" << frame->pts;
                        if (frame->pts != AV_NOPTS_VALUE) {
                            // Rescale PTS to AV_TIME_BASE_Q
                            int64_t pts_in_correct_base = av_rescale_q(frame->pts,
                                fmt_ctx->streams[video_stream_index]->time_base,
                                AV_TIME_BASE_Q);

                            // Ensure we don’t reset to 0 incorrectly
                            if (pts_in_correct_base > 0) {
                                current_pts.store(pts_in_correct_base);
                                qDebug() << "Updated current_pts to:" << current_pts.load();
                            }
                            else {
                                qDebug() << "Warning: Decoded frame has PTS <= 0, keeping last valid PTS.";
                            }
                        }
                        else {
                            qDebug() << "Invalid frame->pts (AV_NOPTS_VALUE)";
                        }

                        QImage img = convertFrameToImage(frame);
                        emit frameDecodedSignal(img);
                
                        frameDecoded = true;
                        break;  // Exit after the first valid frame
                    }

                    if (frameDecoded) {
                        decoding = (requestedTimestamp != lastRequestedTimestamp);
                        break;
                    }
                }
            }
            av_packet_unref(pkt);
        }
    }
}