[FFmpeg-devel] [PATCH] avcodec/v4l2: set sizeimage param for non-raw buffers [fixes #6716]

[Jorge Ramirez-Ortiz]

On 10/04/2017 11:23 AM, wm4 wrote:
> On Wed,  4 Oct 2017 11:17:24 +0200
> Jorge Ramirez-Ortiz <jorge.ramirez-ortiz at linaro.org> wrote:
>
>> Some V4L2 drivers fail to allocate buffers when sizeimage is not set
>> to a max value. This is indeed the case for sp5-mfc [1]
>>
>> Most drivers should be able to calculate this value from the frame
>> dimensions and format - or at least have their own default.
>>
>> However since this work around should not impact those drivers doing
>> the "right thing" this commit just provides such a default.
>>
>> [1] linux.git/drivers/media/platform/s5p-mfc
>> ---
>>   libavcodec/v4l2_context.c | 14 ++++++++++++--
>>   1 file changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/libavcodec/v4l2_context.c b/libavcodec/v4l2_context.c
>> index 297792f..2707ef5 100644
>> --- a/libavcodec/v4l2_context.c
>> +++ b/libavcodec/v4l2_context.c
>> @@ -92,6 +92,8 @@ static inline int v4l2_type_supported(V4L2Context *ctx)
>>   
>>   static inline void v4l2_save_to_context(V4L2Context* ctx, struct v4l2_format_update *fmt)
>>   {
>> +    const int MAX_SIZEIMAGE = 2 * 1024 * 1024;
>> +
>>       ctx->format.type = ctx->type;
>>   
>>       if (fmt->update_avfmt)
>> @@ -101,13 +103,21 @@ static inline void v4l2_save_to_context(V4L2Context* ctx, struct v4l2_format_upd
>>           /* update the sizes to handle the reconfiguration of the capture stream at runtime */
>>           ctx->format.fmt.pix_mp.height = ctx->height;
>>           ctx->format.fmt.pix_mp.width = ctx->width;
>> -        if (fmt->update_v4l2)
>> +        if (fmt->update_v4l2) {
>>               ctx->format.fmt.pix_mp.pixelformat = fmt->v4l2_fmt;
>> +
>> +            /* s5p-mfc requires the user to specify MAX buffer size */
>> +            ctx->format.fmt.pix_mp.plane_fmt[0].sizeimage = MAX_SIZEIMAGE;
>> +        }
>>       } else {
>>           ctx->format.fmt.pix.height = ctx->height;
>>           ctx->format.fmt.pix.width = ctx->width;
>> -        if (fmt->update_v4l2)
>> +        if (fmt->update_v4l2) {
>>               ctx->format.fmt.pix.pixelformat = fmt->v4l2_fmt;
>> +
>> +            /* s5p-mfc requires the user to specify MAX buffer size */
>> +            ctx->format.fmt.pix.sizeimage = MAX_SIZEIMAGE;
>> +        }
>>       }
>>   }
>>   
> Isn't this something that should be fixed in the driver?

yes but it might take forever and I dont know how many other drivers might need it.

>
> Why 2MB?

no analysis done but seems to be enough to hold an encoded frame. Should it be 
any bigger?

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