[FFmpeg-devel] [PATCH v2] avfilter: compress CUDA PTX code if possible

[Timo Rothenpieler]

On 18.06.2021 22:45, Philip Langdale wrote:
> On Sat, 12 Jun 2021 18:47:50 +0200
> Timo Rothenpieler <timo at rothenpieler.org> wrote:
> 
>> ---
>>   .gitignore                      |  1 +
>>   compat/cuda/ptx2c.sh            | 34 ------------
>>   configure                       | 17 ++++++
>>   ffbuild/.gitignore              |  1 +
>>   ffbuild/bin2c.c                 | 76 ++++++++++++++++++++++++++
>>   ffbuild/common.mak              | 28 ++++++++--
>>   libavfilter/Makefile            | 14 +++--
>>   libavfilter/cuda/load_helper.c  | 96
>> +++++++++++++++++++++++++++++++++ libavfilter/cuda/load_helper.h  |
>> 28 ++++++++++ libavfilter/vf_format_cuda.c    |  7 ++-
>>   libavfilter/vf_overlay_cuda.c   |  8 +--
>>   libavfilter/vf_scale_cuda.c     | 24 ++++++---
>>   libavfilter/vf_thumbnail_cuda.c |  7 ++-
>>   libavfilter/vf_yadif_cuda.c     |  7 ++-
>>   14 files changed, 287 insertions(+), 61 deletions(-)
>>   delete mode 100755 compat/cuda/ptx2c.sh
>>   create mode 100644 ffbuild/bin2c.c
>>   create mode 100644 libavfilter/cuda/load_helper.c
>>   create mode 100644 libavfilter/cuda/load_helper.h
> 
> I just had comments about one file:
>   
>> diff --git a/libavfilter/cuda/load_helper.c
>> b/libavfilter/cuda/load_helper.c new file mode 100644
>> index 0000000000..62d644c29a
>> --- /dev/null
>> +++ b/libavfilter/cuda/load_helper.c
>> @@ -0,0 +1,96 @@
>> +/*
>> + * This file is part of FFmpeg.
>> + *
>> + * FFmpeg is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU Lesser General Public
>> + * License as published by the Free Software Foundation; either
>> + * version 2.1 of the License, or (at your option) any later version.
>> + *
>> + * FFmpeg is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + * Lesser General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU Lesser General Public
>> + * License along with FFmpeg; if not, write to the Free Software
>> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
>> 02110-1301 USA
>> + */
>> +
>> +#include "config.h"
>> +
>> +#include "libavutil/hwcontext.h"
>> +#include "libavutil/hwcontext_cuda_internal.h"
>> +#include "libavutil/cuda_check.h"
>> +
>> +#if CONFIG_PTX_COMPRESSION
>> +#include <zlib.h>
>> +#define CHUNK_SIZE 1024 * 64
>> +#endif
>> +
>> +#include "load_helper.h"
>> +
>> +#define CHECK_CU(x) FF_CUDA_CHECK_DL(avctx, cu, x)
>> +
>> +int ff_cuda_load_module(void *avctx, AVCUDADeviceContext *hwctx,
>> CUmodule *cu_module,
>> +                        const unsigned char *data, const unsigned
>> int length) +{
>> +    CudaFunctions *cu = hwctx->internal->cuda_dl;
>> +
>> +#if CONFIG_PTX_COMPRESSION
>> +    z_stream stream = { 0 };
>> +    uint8_t *buf, *tmp;
>> +    uint64_t buf_size;
>> +    int ret;
>> +
>> +    if (inflateInit2(&stream, 32 + 15) != Z_OK) {
> 
> Can you add a comment explaining the magic numbers?

I have no idea what those numbers do, I copied them from http.c and they 
work.

>> +        av_log(avctx, AV_LOG_ERROR, "Error during zlib
>> initialisation: %s\n", stream.msg);
>> +        return AVERROR(ENOSYS);
>> +    }
>> +
>> +    buf_size = CHUNK_SIZE * 4;
>> +    buf = av_realloc(NULL, buf_size);
>> +    if (!buf) {
>> +        inflateEnd(&stream);
>> +        return AVERROR(ENOMEM);
>> +    }
>> +
>> +    stream.next_in = data;
>> +    stream.avail_in = length;
>> +
>> +    do {
>> +        stream.avail_out = buf_size - stream.total_out;
>> +        stream.next_out = buf + stream.total_out;
>> +
>> +        ret = inflate(&stream, Z_FINISH);
>> +        if (ret != Z_OK && ret != Z_STREAM_END) {
>> +            av_log(avctx, AV_LOG_ERROR, "zlib inflate error: %s\n",
>> stream.msg);
>> +            inflateEnd(&stream);
>> +            av_free(buf);
>> +            return AVERROR(EINVAL);
>> +        }
>> +
>> +        if (stream.avail_out == 0) {
>> +            buf_size += CHUNK_SIZE;
>> +            tmp = av_realloc(buf, buf_size);
>> +            if (!tmp) {
>> +                inflateEnd(&stream);
>> +                av_free(buf);
>> +                return AVERROR(ENOMEM);
>> +            }
>> +            buf = tmp;
>> +        }
>> +    } while (ret != Z_STREAM_END);
>> +
>> +    // NULL-terminate string
>> +    // there is guaranteed to be space for this, due to condition in
>> loop
> 
> This is because it will still grow the buffer if avail_out is zero at
> the time you hit Z_STREAM_END?

If avail_out was 0, the condition right above it would have grown it, so 
it has at least one byte free.

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