[libcamera-devel] [PATCH] cam: Limit file write to payload size

[Kieran Bingham]

Hi Laurent,

On 22/08/2020 14:40, Laurent Pinchart wrote:
> The payload size in a captured framebuffer is usually equal to the
> buffer size. However, for compressed formats, the payload may be
> smaller Only write the payload when capturing to a file.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  src/cam/buffer_writer.cpp | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/src/cam/buffer_writer.cpp b/src/cam/buffer_writer.cpp
> index c5a5eb46224a..6305958924a4 100644
> --- a/src/cam/buffer_writer.cpp
> +++ b/src/cam/buffer_writer.cpp
> @@ -64,9 +64,17 @@ int BufferWriter::write(FrameBuffer *buffer, const std::string &streamName)
>  	if (fd == -1)
>  		return -errno;
>  
> -	for (const FrameBuffer::Plane &plane : buffer->planes()) {
> +	for (unsigned int i = 0; i < buffer->planes().size(); ++i) {
> +		const FrameBuffer::Plane &plane = buffer->planes()[i];
> +		const FrameMetadata::Plane &meta = buffer->metadata().planes[i];
> +
>  		void *data = mappedBuffers_[plane.fd.fd()].first;
> -		unsigned int length = plane.length;
> +		unsigned int length = std::min(meta.bytesused, plane.length);
> +
> +		if (length < meta.bytesused)
> +			std::cerr << "payload size " << meta.bytesused
> +				  << " smaller than plane size " << plane.length
> +				  << std::endl;

Is the cerr necessary? If saving out an MJPEG stream from an MJPEG UVC
camera - this would print every frame...

Which is however the use case that makes me believe this patch is useful...

So with that considered either way,

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

>  
>  		ret = ::write(fd, data, length);
>  		if (ret < 0) {
> 

-- 
Regards
--
Kieran