[Libav-user] Fill AVFrame from a Cairo surface

Colossus colossus73 at gmail.com
Thu Aug 26 20:51:14 EEST 2021


Not about how to fill an AVFrame->data with pixels coming for a Cairo
Surface.
Also all the examples are about reading a video file and display it. The
file encode.c
is totally USELESS.

Yeah I took this into an account. Human beings are strange animals. They
reply
only when they are "attacked"...

On Thu, 26 Aug 2021 at 19:46, Paul B Mahol <onemda at gmail.com> wrote:

>
>
> On Thu, Aug 26, 2021 at 6:59 PM Colossus <colossus73 at gmail.com> wrote:
>
>> No more replies? Still on vacations?
>>
>> What's the point to release a good C library to handle videos
>> and don't write a fuck of documentation?
>>
>
> There is documentation and multitude of projects successfully using it.
>
> Your behavior will get you nowhere.
>
>
>>
>> On Wed, 18 Aug 2021 at 13:17, Colossus <colossus73 at gmail.com> wrote:
>>
>>> Ok, I reordered the code. I don't get anymore the annoying message
>>> 'input picture width greater than stride' but I get a crash in
>>> memalloc() called
>>> by av_send_frame().
>>>
>>> *This is the gdb output:*
>>> Thread 1 "imagination" received signal SIGABRT, Aborted.
>>> __GI_raise (sig=sig at entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
>>> 50 ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
>>> (gdb) bt
>>> #0  __GI_raise (sig=sig at entry=6) at
>>> ../sysdeps/unix/sysv/linux/raise.c:50
>>> #1  0x00007ffff5518537 in __GI_abort () at abort.c:79
>>> #2  0x00007ffff5571768 in __libc_message (action=action at entry=do_abort,
>>> fmt=fmt at entry=0x7ffff567fe2d "%s\n")
>>>     at ../sysdeps/posix/libc_fatal.c:155
>>> #3  0x00007ffff5578a5a in malloc_printerr (str=str at entry=0x7ffff5682110
>>> "malloc_consolidate(): invalid chunk size")
>>>     at malloc.c:5347
>>> #4  0x00007ffff5579918 in malloc_consolidate (av=av at entry=0x7ffff56b1b80
>>> <main_arena>) at malloc.c:4477
>>> #5  0x00007ffff557b755 in _int_malloc (av=av at entry=0x7ffff56b1b80
>>> <main_arena>, bytes=bytes at entry=16288) at malloc.c:3699
>>> #6  0x00007ffff557c4af in _int_memalign
>>>     (av=av at entry=0x7ffff56b1b80 <main_arena>, alignment=alignment at entry=64,
>>> bytes=bytes at entry=16176) at malloc.c:4684
>>> #7  0x00007ffff557d55c in _mid_memalign (alignment=64, bytes=16176,
>>> address=<optimized out>) at malloc.c:3312
>>> #8  0x00007ffff1e9fb2a in x264_malloc () at
>>> /lib/x86_64-linux-gnu/libx264.so.160
>>> #9  0x00007ffff1eba75c in  () at /lib/x86_64-linux-gnu/libx264.so.160
>>> #10 0x00007ffff1ebe6b0 in  () at /lib/x86_64-linux-gnu/libx264.so.160
>>> #11 0x00007ffff1f27957 in  () at /lib/x86_64-linux-gnu/libx264.so.160
>>> #12 0x00007ffff1ea4aa1 in x264_encoder_encode () at
>>> /lib/x86_64-linux-gnu/libx264.so.160
>>> #13 0x00007ffff62df6d8 in  () at /lib/x86_64-linux-gnu/libavcodec.so.58
>>> #14 0x00007ffff6094c37 in avcodec_encode_video2 () at
>>> /lib/x86_64-linux-gnu/libavcodec.so.58
>>> #15 0x00007ffff6095012 in  () at /lib/x86_64-linux-gnu/libavcodec.so.58
>>> #16 0x00007ffff609519f in *avcodec_send_frame* () at
>>> /lib/x86_64-linux-gnu/libavcodec.so.58
>>> #17 0x000055555557aaae in img_export_encode_av_frame
>>>     (pkt=0x5555556e6d60, ctx=0x55555643cb40, fmt=0x5555564859c0,
>>> frame=<optimized out>) at export.c:968
>>>
>>> And this is the code:
>>> static gboolean img_export_frame_to_avframe(img_window_struct *img,
>>> cairo_surface_t *surface)
>>> {
>>> static gint i = 0;
>>>
>>> gint width, height, stride, row, col, offset, ret;
>>> uint8_t  *pix, *data;
>>> AVFrame *frame;
>>>
>>> /* Image info and pixel data */
>>> width  = cairo_image_surface_get_width( surface );
>>> height = cairo_image_surface_get_height( surface );
>>> stride = cairo_image_surface_get_stride( surface );
>>> pix    = cairo_image_surface_get_data( surface );
>>>
>>> /* Initialize AVFrame to be sent to the encoder */
>>> frame = av_frame_alloc();
>>> frame->format = img->codec_context->pix_fmt;
>>> frame->width  = img->video_size[0];
>>> frame->height = img->video_size[1];
>>> av_frame_get_buffer(frame, 32);
>>>
>>>      /* Fill the frame data with pixels from the Cairo surface */
>>> for( row = 0; row < height; row++ )
>>> {
>>> data = pix + row * stride;
>>> for( col = 0; col < width; col++ )
>>> {
>>> frame->data[0][row * frame->linesize[0] + col] = data[2];
>>> frame->data[1][row * frame->linesize[1] + col] = data[1];
>>> frame->data[2][row * frame->linesize[2] + col] = data[0];
>>> data += 4;
>>> }
>>> frame->pts = i;
>>> i++;
>>> }
>>> //sws_scale(img->sws_ctx, pix, img->video_frame->linesize, 0,
>>> img->video_frame->height, img->video_frame->data, sws_frame->linesize);
>>>
>>> ret = img_export_encode_av_frame(frame, img->video_format_context,
>>> img->codec_context, &img->video_packet);
>>>
>>> if (frame)
>>> {
>>> av_frame_free(&frame);
>>> frame = NULL;
>>> }
>>> return ret;
>>> }
>>>
>>> gboolean img_export_encode_av_frame(AVFrame *frame, AVFormatContext
>>> *fmt, AVCodecContext *ctx, AVPacket *pkt)
>>> {
>>> gint ret;
>>>
>>>     /* send the frame to the encoder */
>>>     ret = *avcodec_send_frame*(ctx, frame);
>>>     if (ret < 0)
>>> {
>>> g_print("Av error: %s\n",av_err2str(ret));
>>> g_print("Error sending a frame for encoding\n");
>>> return FALSE;
>>> }
>>>     while (ret >= 0)
>>>     {
>>>         ret = avcodec_receive_packet(ctx, pkt);
>>>         if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
>>> return TRUE;
>>>         else if (ret < 0)
>>> g_print("Error during encoding\n");
>>>
>>> av_interleaved_write_frame(fmt, pkt);
>>> av_packet_unref(pkt);
>>> return FALSE;
>>>     }
>>>     return TRUE;
>>> }
>>>
>>> What can be the cause of the crash now?
>>>
>>> Thanks
>>>
>>> On Mon, 16 Aug 2021 at 16:35, Nicolas George <george at nsup.org> wrote:
>>>
>>>> Colossus (12021-08-16):
>>>> > I told you I did and avcodec_send_frame() is the one that throws that
>>>> error.
>>>>
>>>> I will trust the code I see. Re-post your code once you have fixed the
>>>> order of the function calls and checked all the return values properly,
>>>> if it still does not work.
>>>>
>>>> --
>>>>   Nicolas George
>>>> _______________________________________________
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>>>>
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>>>> libav-user-request at ffmpeg.org with subject "unsubscribe".
>>>>
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