[FFmpeg-devel] [PATCH 6/7] libavfilter/vf_sr.c: Removes uint8 -> float and float -> uint8 conversions.

Pedro Arthur bygrandao at gmail.com
Tue Aug 14 22:07:14 EEST 2018


2018-08-14 15:45 GMT-03:00 Rostislav Pehlivanov <atomnuker at gmail.com>:
> On Thu, 2 Aug 2018 at 20:00, Sergey Lavrushkin <dualfal at gmail.com> wrote:
>
>> This patch removes conversions, declared inside the sr filter, and uses
>> libswscale inside
>> the filter to perform them for only Y channel of input. The sr filter
>> still has uint
>> formats as input, as it does not use chroma channels in models and these
>> channels are
>> upscaled using libswscale, float formats for input would cause unnecessary
>> conversions
>> during scaling for these channels.
>>
>> ---
>>  libavfilter/vf_sr.c | 134
>> +++++++++++++++++++---------------------------------
>>  1 file changed, 48 insertions(+), 86 deletions(-)
>>
>> diff --git a/libavfilter/vf_sr.c b/libavfilter/vf_sr.c
>> index 944a0e28e7..5ad1baa4c0 100644
>> --- a/libavfilter/vf_sr.c
>> +++ b/libavfilter/vf_sr.c
>> @@ -45,8 +45,8 @@ typedef struct SRContext {
>>      DNNModel *model;
>>      DNNData input, output;
>>      int scale_factor;
>> -    struct SwsContext *sws_context;
>> -    int sws_slice_h;
>> +    struct SwsContext *sws_contexts[3];
>> +    int sws_slice_h, sws_input_linesize, sws_output_linesize;
>>  } SRContext;
>>
>>  #define OFFSET(x) offsetof(SRContext, x)
>> @@ -95,6 +95,10 @@ static av_cold int init(AVFilterContext *context)
>>          return AVERROR(EIO);
>>      }
>>
>> +    sr_context->sws_contexts[0] = NULL;
>> +    sr_context->sws_contexts[1] = NULL;
>> +    sr_context->sws_contexts[2] = NULL;
>> +
>>      return 0;
>>  }
>>
>> @@ -110,6 +114,7 @@ static int query_formats(AVFilterContext *context)
>>          av_log(context, AV_LOG_ERROR, "could not create formats list\n");
>>          return AVERROR(ENOMEM);
>>      }
>> +
>>      return ff_set_common_formats(context, formats_list);
>>  }
>>
>> @@ -140,21 +145,31 @@ static int config_props(AVFilterLink *inlink)
>>      else{
>>          outlink->h = sr_context->output.height;
>>          outlink->w = sr_context->output.width;
>> +        sr_context->sws_contexts[1] =
>> sws_getContext(sr_context->input.width, sr_context->input.height,
>> AV_PIX_FMT_GRAY8,
>> +
>>  sr_context->input.width, sr_context->input.height, AV_PIX_FMT_GRAYF32,
>> +                                                     0, NULL, NULL, NULL);
>> +        sr_context->sws_input_linesize = sr_context->input.width << 2;
>> +        sr_context->sws_contexts[2] =
>> sws_getContext(sr_context->output.width, sr_context->output.height,
>> AV_PIX_FMT_GRAYF32,
>> +
>>  sr_context->output.width, sr_context->output.height, AV_PIX_FMT_GRAY8,
>> +                                                     0, NULL, NULL, NULL);
>> +        sr_context->sws_output_linesize = sr_context->output.width << 2;
>> +        if (!sr_context->sws_contexts[1] || !sr_context->sws_contexts[2]){
>> +            av_log(context, AV_LOG_ERROR, "could not create SwsContext
>> for conversions\n");
>> +            return AVERROR(ENOMEM);
>> +        }
>>          switch (sr_context->model_type){
>>          case SRCNN:
>> -            sr_context->sws_context = sws_getContext(inlink->w,
>> inlink->h, inlink->format,
>> -                                                     outlink->w,
>> outlink->h, outlink->format, SWS_BICUBIC, NULL, NULL, NULL);
>> -            if (!sr_context->sws_context){
>> -                av_log(context, AV_LOG_ERROR, "could not create
>> SwsContext\n");
>> +            sr_context->sws_contexts[0] = sws_getContext(inlink->w,
>> inlink->h, inlink->format,
>> +                                                         outlink->w,
>> outlink->h, outlink->format,
>> +                                                         SWS_BICUBIC,
>> NULL, NULL, NULL);
>> +            if (!sr_context->sws_contexts[0]){
>> +                av_log(context, AV_LOG_ERROR, "could not create
>> SwsContext for scaling\n");
>>                  return AVERROR(ENOMEM);
>>              }
>>              sr_context->sws_slice_h = inlink->h;
>>              break;
>>          case ESPCN:
>> -            if (inlink->format == AV_PIX_FMT_GRAY8){
>> -                sr_context->sws_context = NULL;
>> -            }
>> -            else{
>> +            if (inlink->format != AV_PIX_FMT_GRAY8){
>>                  sws_src_h = sr_context->input.height;
>>                  sws_src_w = sr_context->input.width;
>>                  sws_dst_h = sr_context->output.height;
>> @@ -184,13 +199,14 @@ static int config_props(AVFilterLink *inlink)
>>                      sws_dst_w = AV_CEIL_RSHIFT(sws_dst_w, 2);
>>                      break;
>>                  default:
>> -                    av_log(context, AV_LOG_ERROR, "could not create
>> SwsContext for input pixel format");
>> +                    av_log(context, AV_LOG_ERROR, "could not create
>> SwsContext for scaling for given input pixel format");
>>                      return AVERROR(EIO);
>>                  }
>> -                sr_context->sws_context = sws_getContext(sws_src_w,
>> sws_src_h, AV_PIX_FMT_GRAY8,
>> -                                                         sws_dst_w,
>> sws_dst_h, AV_PIX_FMT_GRAY8, SWS_BICUBIC, NULL, NULL, NULL);
>> -                if (!sr_context->sws_context){
>> -                    av_log(context, AV_LOG_ERROR, "could not create
>> SwsContext\n");
>> +                sr_context->sws_contexts[0] = sws_getContext(sws_src_w,
>> sws_src_h, AV_PIX_FMT_GRAY8,
>> +                                                             sws_dst_w,
>> sws_dst_h, AV_PIX_FMT_GRAY8,
>> +                                                             SWS_BICUBIC,
>> NULL, NULL, NULL);
>> +                if (!sr_context->sws_contexts[0]){
>> +                    av_log(context, AV_LOG_ERROR, "could not create
>> SwsContext for scaling\n");
>>                      return AVERROR(ENOMEM);
>>                  }
>>                  sr_context->sws_slice_h = sws_src_h;
>> @@ -201,61 +217,12 @@ static int config_props(AVFilterLink *inlink)
>>      }
>>  }
>>
>> -typedef struct ThreadData{
>> -    uint8_t *data;
>> -    int data_linesize, height, width;
>> -} ThreadData;
>> -
>> -static int uint8_to_float(AVFilterContext *context, void *arg, int jobnr,
>> int nb_jobs)
>> -{
>> -    SRContext *sr_context = context->priv;
>> -    const ThreadData *td = arg;
>> -    const int slice_start = (td->height *  jobnr     ) / nb_jobs;
>> -    const int slice_end   = (td->height * (jobnr + 1)) / nb_jobs;
>> -    const uint8_t *src = td->data + slice_start * td->data_linesize;
>> -    float *dst = sr_context->input.data + slice_start * td->width;
>> -    int y, x;
>> -
>> -    for (y = slice_start; y < slice_end; ++y){
>> -        for (x = 0; x < td->width; ++x){
>> -            dst[x] = (float)src[x] / 255.0f;
>> -        }
>> -        src += td->data_linesize;
>> -        dst += td->width;
>> -    }
>> -
>> -    return 0;
>> -}
>> -
>> -static int float_to_uint8(AVFilterContext *context, void *arg, int jobnr,
>> int nb_jobs)
>> -{
>> -    SRContext *sr_context = context->priv;
>> -    const ThreadData *td = arg;
>> -    const int slice_start = (td->height *  jobnr     ) / nb_jobs;
>> -    const int slice_end   = (td->height * (jobnr + 1)) / nb_jobs;
>> -    const float *src = sr_context->output.data + slice_start * td->width;
>> -    uint8_t *dst = td->data + slice_start * td->data_linesize;
>> -    int y, x;
>> -
>> -    for (y = slice_start; y < slice_end; ++y){
>> -        for (x = 0; x < td->width; ++x){
>> -            dst[x] = (uint8_t)(255.0f * FFMIN(src[x], 1.0f));
>> -        }
>> -        src += td->width;
>> -        dst += td->data_linesize;
>> -    }
>> -
>> -    return 0;
>> -}
>> -
>>  static int filter_frame(AVFilterLink *inlink, AVFrame *in)
>>  {
>>      AVFilterContext *context = inlink->dst;
>>      SRContext *sr_context = context->priv;
>>      AVFilterLink *outlink = context->outputs[0];
>>      AVFrame *out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
>> -    ThreadData td;
>> -    int nb_threads;
>>      DNNReturnType dnn_result;
>>
>>      if (!out){
>> @@ -268,28 +235,23 @@ static int filter_frame(AVFilterLink *inlink,
>> AVFrame *in)
>>      out->width = sr_context->output.width;
>>      switch (sr_context->model_type){
>>      case SRCNN:
>> -        sws_scale(sr_context->sws_context, (const uint8_t **)in->data,
>> in->linesize,
>> +        sws_scale(sr_context->sws_contexts[0], (const uint8_t
>> **)in->data, in->linesize,
>>                    0, sr_context->sws_slice_h, out->data, out->linesize);
>> -        td.data = out->data[0];
>> -        td.data_linesize = out->linesize[0];
>> -        td.height = out->height;
>> -        td.width = out->width;
>> +
>> +        sws_scale(sr_context->sws_contexts[1], (const uint8_t
>> **)out->data, out->linesize,
>> +                  0, out->height, (uint8_t *
>> const*)(&sr_context->input.data), &sr_context->sws_input_linesize);
>>          break;
>>      case ESPCN:
>> -        if (sr_context->sws_context){
>> -            sws_scale(sr_context->sws_context, (const uint8_t
>> **)(in->data + 1), in->linesize + 1,
>> +        if (sr_context->sws_contexts[0]){
>> +            sws_scale(sr_context->sws_contexts[0], (const uint8_t
>> **)(in->data + 1), in->linesize + 1,
>>                        0, sr_context->sws_slice_h, out->data + 1,
>> out->linesize + 1);
>> -            sws_scale(sr_context->sws_context, (const uint8_t
>> **)(in->data + 2), in->linesize + 2,
>> +            sws_scale(sr_context->sws_contexts[0], (const uint8_t
>> **)(in->data + 2), in->linesize + 2,
>>                        0, sr_context->sws_slice_h, out->data + 2,
>> out->linesize + 2);
>>          }
>> -        td.data = in->data[0];
>> -        td.data_linesize = in->linesize[0];
>> -        td.height = in->height;
>> -        td.width = in->width;
>> -    }
>>
>> -    nb_threads = ff_filter_get_nb_threads(context);
>> -    context->internal->execute(context, uint8_to_float, &td, NULL,
>> FFMIN(td.height, nb_threads));
>> +        sws_scale(sr_context->sws_contexts[1], (const uint8_t
>> **)in->data, in->linesize,
>> +                  0, in->height, (uint8_t *
>> const*)(&sr_context->input.data), &sr_context->sws_input_linesize);
>> +    }
>>      av_frame_free(&in);
>>
>>      dnn_result =
>> (sr_context->dnn_module->execute_model)(sr_context->model);
>> @@ -298,17 +260,15 @@ static int filter_frame(AVFilterLink *inlink,
>> AVFrame *in)
>>          return AVERROR(EIO);
>>      }
>>
>> -    td.data = out->data[0];
>> -    td.data_linesize = out->linesize[0];
>> -    td.height = out->height;
>> -    td.width = out->width;
>> -    context->internal->execute(context, float_to_uint8, &td, NULL,
>> FFMIN(td.height, nb_threads));
>> +    sws_scale(sr_context->sws_contexts[2], (const uint8_t
>> **)(&sr_context->output.data), &sr_context->sws_output_linesize,
>> +              0, out->height, (uint8_t * const*)out->data, out->linesize);
>>
>>      return ff_filter_frame(outlink, out);
>>  }
>>
>>  static av_cold void uninit(AVFilterContext *context)
>>  {
>> +    int i;
>>      SRContext *sr_context = context->priv;
>>
>>      if (sr_context->dnn_module){
>> @@ -316,8 +276,10 @@ static av_cold void uninit(AVFilterContext *context)
>>          av_freep(&sr_context->dnn_module);
>>      }
>>
>> -    if (sr_context->sws_context){
>> -        sws_freeContext(sr_context->sws_context);
>> +    for (i = 0; i < 3; ++i){
>> +        if (sr_context->sws_contexts[i]){
>> +            sws_freeContext(sr_context->sws_contexts[i]);
>> +        }
>>      }
>>  }
>>
>> --
>> 2.14.1
>>
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
>
> You are planning to remove *all* conversion still, right? Its still
> unacceptable that there *are* conversions.

They are here because it is the most efficient way to do it. The
filter works only on luminance channel therefore we only apply
conversion to Y channel, and bicubic upscale to chrominance.
I can't see how one can achieve the same result, without doing useless
computations, if not in this way.

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> ffmpeg-devel at ffmpeg.org
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