[Libav-user] Fill AVFrame from a Cairo surface

Paul B Mahol onemda at gmail.com
Thu Aug 26 22:19:42 EEST 2021 

On Thu, Aug 26, 2021 at 9:17 PM Colossus <colossus73 at gmail.com> wrote:

> On Thu, 26 Aug 2021 at 21:12, Paul B Mahol <onemda at gmail.com> wrote:
>
>>
>> Probably because you mux incorrectly...
>>
>
> Most probably but where is the documentation about muxing "correctly"?
> I check the return value of all the av functions I call. *No errors.*
>
> Can you please point to some projects who *don't* load a video file
> and encode into another but instead take a piece of data from
> memory and fill the AVFrame->data? That would be very very helpful.
>

send/receive packet/frame works in loops, and you need to follow examples,
sorry but my free consulting time is over.


>
> Thanks
> Giuseppe
>
>>
>>
>>>
>>> if you want to give a look to the software:
>>> http://imagination.sourceforge.net/
>>>
>>> Many thanks
>>> Giuseppe
>>>
>>> On Thu, 26 Aug 2021 at 20:16, Paul B Mahol <onemda at gmail.com> wrote:
>>>
>>>>
>>>>
>>>> On Wed, Aug 18, 2021 at 1:17 PM 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);
>>>>>
>>>>
>>>> Why 32?, in doxy 0 is recommended, unless programmer know exactly what
>>>> he is doing.
>>>>
>>>>
>>>>>      /* 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?
>>>>>
>>>>
>>>> Check with valgrind or similar for buffer overreads or overwrites.
>>>>
>>>>
>>>>>
>>>>> 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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>>>>>>
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