[FFmpeg-devel] [PATCH 1/1] add option in file.c: pkt_size to setmax_packet_size

[1+1=10]

This modification references the max_packet_size assignment method in other protocols, such as the one in udp.c；
This operation not only maintains the original setting but also adds custom settings；
For example, when reading a local file, you can first set pkt_size using av_dict_set and then pass the option in avio_open2；
This is mainly to deal with the situation where the IoT device has small memory, so that max_packet_size can be customized；


> ---
> libavformat/file.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/libavformat/file.c b/libavformat/file.c
> index 6a66040b65..8099a7e931 100644
> --- a/libavformat/file.c
> +++ b/libavformat/file.c
> @@ -94,6 +94,7 @@ typedef struct FileContext {
>     int fd;
>     int trunc;
>     int blocksize;
> +    int pkt_size;
>     int follow;
>     int seekable;
> #if HAVE_DIRENT_H
> @@ -106,6 +107,7 @@ static const AVOption file_options[] = {
>     { "blocksize", "set I/O operation maximum block size", offsetof(FileContext, blocksize), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
>     { "follow", "Follow a file as it is being written", offsetof(FileContext, follow), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, AV_OPT_FLAG_DECODING_PARAM },
>     { "seekable", "Sets if the file is seekable", offsetof(FileContext, seekable), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 0, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_ENCODING_PARAM },
> +    { "pkt_size", "Maximum file packet size", offsetof(FileContext, pkt_size), AV_OPT_TYPE_INT, { .i64 = 262144 }, -1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_ENCODING_PARAM },
>     { NULL }
> };
> 
> @@ -313,7 +315,7 @@ static int file_open(URLContext *h, const char *filename, int flags)
>     /* Buffer writes more than the default 32k to improve throughput especially
>      * with networked file systems */
>     if (!h->is_streamed && flags & AVIO_FLAG_WRITE)
> -        h->min_packet_size = h->max_packet_size = 262144;
> +        h->min_packet_size = h->max_packet_size = c->pkt_size;


What's the use case?




1+1=10
1441923451 at qq.com



        



         原始邮件
         
       
发件人：Zhao Zhili <quinkblack at foxmail.com>
发件时间：2025年7月17日 23:01
收件人：FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>
抄送：1441923451 <1441923451 at qq.com>
主题：Re: [FFmpeg-devel] [PATCH 1/1] add option in file.c: pkt_size to setmax_packet_size





> On Jul 17, 2025, at 22:05, yangsen5 via ffmpeg-devel <ffmpeg-devel at ffmpeg.org> wrote:
> 
> From: yangsen5 <1441923451 at qq.com>
> 
> Signed-off-by: yangsen5 <1441923451 at qq.com>
> ---
> libavformat/file.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/libavformat/file.c b/libavformat/file.c
> index 6a66040b65..8099a7e931 100644
> --- a/libavformat/file.c
> +++ b/libavformat/file.c
> @@ -94,6 +94,7 @@ typedef struct FileContext {
>     int fd;
>     int trunc;
>     int blocksize;
> +    int pkt_size;
>     int follow;
>     int seekable;
> #if HAVE_DIRENT_H
> @@ -106,6 +107,7 @@ static const AVOption file_options[] = {
>     { "blocksize", "set I/O operation maximum block size", offsetof(FileContext, blocksize), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
>     { "follow", "Follow a file as it is being written", offsetof(FileContext, follow), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, AV_OPT_FLAG_DECODING_PARAM },
>     { "seekable", "Sets if the file is seekable", offsetof(FileContext, seekable), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 0, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_ENCODING_PARAM },
> +    { "pkt_size", "Maximum file packet size", offsetof(FileContext, pkt_size), AV_OPT_TYPE_INT, { .i64 = 262144 }, -1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_ENCODING_PARAM },
>     { NULL }
> };
> 
> @@ -313,7 +315,7 @@ static int file_open(URLContext *h, const char *filename, int flags)
>     /* Buffer writes more than the default 32k to improve throughput especially
>      * with networked file systems */
>     if (!h->is_streamed && flags & AVIO_FLAG_WRITE)
> -        h->min_packet_size = h->max_packet_size = 262144;
> +        h->min_packet_size = h->max_packet_size = c->pkt_size;

What's the use case?

> 
>     if (c->seekable >= 0)
>         h->is_streamed = !c->seekable;
> -- 
> 2.34.1
> 
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