[Libav-user] [External] (no subject)

Tue Sep 25 00:35:32 EEST 2018

Hi Niraj

Thanks for taking the time to respond to the question. I added the options
you recommend. I don't have a file or a image source to open - I already
have a AVPacket. I just opened a dummy format and format context and set
the options that your mentioned.
I still see the same error when I call swscaler - bad src image pointers.

Thanks

--
Jimmy

On Mon, Sep 24, 2018 at 12:48 PM Niraj Gandha <niraj.gandha at einfochips.com>
wrote:

> Use this code Jimmy Bhaktha....
>
> Code for the issue and getting rgb frames from raw H.264 Frame  is as
> follows:
>
> avcodec_register_all(); av_register_all(); avformat_network_init();
> AVDictionary *options = NULL;
> AVFormatContext *refrenceFormatCtx = NULL;
> AVInputFormat *fmts = av_find_input_format("h264");
> char errorsdef[100];
> AVCodecContext* codec_ctx = NULL;
> int video_stream_index = 0;
> SwsContext *img_convert_ctx = NULL;
> AVFrame* picture_yuv = NULL;
> AVFrame* picture_rgb = NULL;
> uint8_t* picture_buffer_rgb;
> uint8_t *rgb_image_data;
> int sizeofrgbpicture = 0;
> int initialize_rgb_requirements=1;
> picture_yuv = av_frame_alloc();
> av_dict_set(&options, "flags", "bicubic", 0);
> av_opt_set(refrenceFormatCtx,"f","h264", AV_OPT_SEARCH_CHILDREN);
> av_opt_set(refrenceFormatCtx,"codec:v","h264",AV_OPT_SEARCH_CHILDREN);
> av_opt_set(refrenceFormatCtx,"probesize","32M", AV_OPT_SEARCH_CHILDREN); //
> Open video file int err =
> avformat_open_input(&refrenceFormatCtx,"tcp://192.168.42.129:2226", fmts,
> &options);
> if (!options) {
> int dict_count = av_dict_count(options);
> qDebug() << "dict_count " << dict_count;
> }
> av_strerror(err,errorsdef,100);
> qDebug() << "OPening Stream error: "<< err << " "<< errorsdef;
> if (refrenceFormatCtx!=NULL){
> err = avformat_find_stream_info(refrenceFormatCtx, &options);
> if( err< 0){
> av_strerror(err,errorsdef,100);
> qDebug() << "Not able to find stream: "<< err << " "<< errorsdef;
>      }
> }else{
> qDebug() << "referencecontext null";
> exit(1);
> } //search video stream
> for (int i = 0; i < (int)refrenceFormatCtx->nb_streams; i++)
> {
> AVStream* s = refrenceFormatCtx->streams[i];
> if (s->codec == NULL){
> continue;
> }
> codec_ctx = (s->codec);
> if (codec_ctx->codec_type == AVMEDIA_TYPE_VIDEO){
> video_stream_index = i;
> }
> }
> AVPacket packet; av_init_packet(&packet); //open output file
> AVFormatContext* output_ctx = avformat_alloc_context();
> AVStream* stream = NULL; //start reading packets from stream and emit
> data pointer to slot
> av_read_play(refrenceFormatCtx); //play RTSP
> avcodec_copy_context(codec_ctx,
> refrenceFormatCtx->streams[video_stream_index]->codec);
> if (avcodec_open2(codec_ctx, avcodec_find_decoder(AV_CODEC_ID_H264), NULL)
> < 0){
> qDebug() << "avcodec_open2 null";
> } while (av_read_frame(refrenceFormatCtx, &packet) >= 0) {
> if (packet.stream_index == video_stream_index) { //packet is video
> if (stream == NULL) { //create stream in file
> stream = avformat_new_stream(output_ctx,
> refrenceFormatCtx->streams[video_stream_index]->codec->codec);
> avcodec_copy_context(stream->codec,
> refrenceFormatCtx->streams[video_stream_index]->codec);
> stream->sample_aspect_ratio =
> refrenceFormatCtx->streams[video_stream_index]->codec->sample_aspect_ratio;
> } int check = 0; packet.stream_index = stream->id; int result = av
> codec_decode_video2(codec_ctx, picture_yuv, &check, &packet);
> av_free_packet(&packet);
> av_packet_unref(&packet);
> if(result <= 0 || check == 0){
> continue;
> }
> if(initialize_rgb_requirements) {
> sizeofrgbpicture = avpicture_get_size(AV_PIX_FMT_RGB24, codec_ctx->width,
> codec_ctx->height);
> picture_rgb = av_frame_alloc();
> picture_buffer_rgb = (uint8_t*) (av_malloc(sizeofrgbpicture));
> avpicture_fill((AVPicture *) picture_rgb, picture_buffer_rgb,
> AV_PIX_FMT_RGB24, codec_ctx->width, codec_ctx->height);
> img_convert_ctx = sws_getContext(codec_ctx->width, codec_ctx->height,
> AV_PIX_FMT_YUV420P, codec_ctx->width, codec_ctx->height, AV_PIX_FMT_RGB24,
> SWS_BICUBIC, NULL, NULL, NULL); initialize_rgb_requirements=0;
> }
> int height = 0;
> if(picture_yuv->data != NULL) { height = sws_scale(img_convert_ctx,
> ((AVPicture*)picture_yuv)->data, ((AVPicture*)picture_yuv)->linesize, 0,
> codec_ctx->height,
> ((AVPicture*)picture_rgb)->data,((AVPicture*)picture_rgb)->linesize);
> }
> rgb_image_data = (uint8_t *)malloc(sizeofrgbpicture * sizeof(uint8_t));
> int ret = avpicture_layout((AVPicture *)picture_rgb, AV_PIX_FMT_RGB24,
> codec_ctx->width, codec_ctx->height, rgb_image_data, sizeofrgbpicture);
> emit imageQueued(rgb_image_data, codec_ctx->width,codec_ctx->height);
> }
> msleep(1);
> }
> av_freep(picture_buffer_rgb);
> av_frame_free(&picture_rgb);
> avio_close(output_ctx->pb);
> avformat_free_context(output_ctx);
> avformat_close_input(&refrenceFormatCtx);
>
> we have to tell ffmpeg that the format is h264. For that I have
> used AVInputFormat, to set other options like video codec and probesize, I
> have used av_op_set(). To set the default flags in ffmpeg, I have
> used av_dict_set(). I have emitted the data pointer to my required slot. If
> any one wants to create a file from it, then it can generate .ppm file by
> writing this pointer into file.
>
>
>
>
> * Thanks & Regards, *
> *Niraj Gandha*
> Trainee Engineer | PES
>
>
>
>
> Tel: 7016116093 | Cell: 9408781216 | Ext.: 3318
> Product Engineering Services
> Software | System | Silicon | Mechanical
> <http://www.einfochips.com/>
> www.einfochips.com
>  |
> niraj.gandha at einfochips.com
>
>
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> 20 Years of Engineering Innovation & Excellence
> Recognized as 'Leader' in Zinnov's Global Service Providers Rating-2015
> *From:* Libav-user <libav-user-bounces at ffmpeg.org> on behalf of Jimmy
> Bhaktha <jimmy at accelrobotics.com>
> *Sent:* Tuesday, September 25, 2018 12:55:49 AM
> *To:* libav-user at ffmpeg.org
> *Subject:* [External] [Libav-user] (no subject)
>
> CAUTION: This email originated from outside of the organization. Do not
> click links or open attachments unless you recognize the sender and know
> the content is safe.
>
> Hi
>
> I am working on an application based on FFMPEG version 3.4.2 where the
> RTSP packets from the camera are captured and store using python. The
> decoder application is run later.  The application receives a  byte array
> which is the actual packet. The goal is to decode the received packet and
> convert it to RGB from YUV.
>
> When I feed it packets I see the following output
>
> Creating the codec h264
> Creating the codec context
> [h264 @ 0x557a3846d880] nal_unit_type: 7, nal_ref_idc: 3
> [h264 @ 0x557a3846d880] nal_unit_type: 8, nal_ref_idc: 3
>
>
> [h264 @ 0x557a3846d880] nal_unit_type: 5, nal_ref_idc: 3
>
>
> [h264 @ 0x557a3846d880] Reinit context to 2688x1520, pix_fmt: yuvj420p
>
>
> avcodec_send_packet=0
>
>
> avcodec_receive_frame=0, pCodecCtx->frame_number=1
> [swscaler @ 0x557a385fdb20] bad src image pointers
> avcodec_send_packet=0
>
>
> avcodec_receive_frame=0, pCodecCtx->frame_number=2
> [swscaler @ 0x557a385fdb20] bad src image pointers
>
> I was  wondering why the swscaler is complaining about bad src images.
>
> Here is the sequence of calls in my code
>
> 1.  av_packet_alloc() and av_packet_init()
>      - copy the encoded image to packet->data (I extend it by
> AV_INPUT_BUFFER_PADDING_SIZE and set the memory to zero
> 2.  av_register_all();
> 3.  Create the codec and Codec Context for h264 and open it.
>     - I Copy the extra data from the encoded frame to this context.
> 4. Allocate the memory for the frames (YUV and RGB)
> 5. First time using the coded I call decode - I see the codec context now
> has the correct values for height and width.
>     - For decoding I use the avcodec_send_packet and check in a while loop
> for avcodec_receive_frame() I see the number of decoded frames in the codec
> context goes up (pCodecCtx->frame_number)
> 6. Use this codec context to set up the sws_context
> 7. Use the sws_context and the YUV frame decoded to get the RGB frame.
>
>
> --
> Jimmy Bhaktha
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-- 
Jimmy Bhaktha
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