[FFmpeg-devel] [PATCH v2] avformat/mov: fix buffering issue for special HTTP(s) mp4.

[Zhao Zhili]

On Tue, 2022-12-20 at 09:20 +0000, Chen, Jinkai wrote:
> Problem:
> Using ffplay play on these sources:
> https://ali-sprite-video.yyouwang.com/video/works/202211/1667997073624_73.mp4
> https://images.voghion.com/productImages/04_01_C_30011_2020220106GiuseppeFanara0012.mp4
> 
> Solution:
> Add a private option, it will use separated IO context(HTTP
> connection)
> for each AVStream. Preventing from reading audio and video in
> long distance(offset), which cause seeking(HTTP request) frequently.
> 
> Storing the user options when open input,
> and make sure that can be passed to demuxer context.

I'm afraid such workaround is difficult to maintain for long term. You
can achieve the same result (with a little overhead) with multiple
AVFormatContexts, which is still abuse of network transport. The only
elegant way I can get to handle such broken files is download to local
storage and remux.

> 
> Signed-off-by: Gamhoi Chan <chenjinkai at agora.io<mailto:
> chenjinkai at agora.io>>
> ---
> libavformat/avformat.c |  1 +
> libavformat/demux.c    |  5 ++++-
> libavformat/internal.h |  5 +++++
> libavformat/isom.h     |  1 +
> libavformat/mov.c      | 14 +++++++++++++-
> 5 files changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/libavformat/avformat.c b/libavformat/avformat.c
> index 19c7219471..4453727f34 100644
> --- a/libavformat/avformat.c
> +++ b/libavformat/avformat.c
> @@ -129,6 +129,7 @@ void avformat_free_context(AVFormatContext *s)
>     av_freep(&s->chapters);
>     av_dict_free(&s->metadata);
>     av_dict_free(&si->id3v2_meta);
> +    av_dict_free(&si->options);
>     av_packet_free(&si->pkt);
>     av_packet_free(&si->parse_pkt);
>     av_freep(&s->streams);
> diff --git a/libavformat/demux.c b/libavformat/demux.c
> index 2dfd82a63c..2377bfdab0 100644
> --- a/libavformat/demux.c
> +++ b/libavformat/demux.c
> @@ -237,8 +237,11 @@ int avformat_open_input(AVFormatContext **ps,
> const char *filename,
>     if (fmt)
>         s->iformat = fmt;
> 
> -    if (options)
> +    if (options) {
>         av_dict_copy(&tmp, *options, 0);
> +        si->options = NULL;
> +        av_dict_copy(&si->options, *options, 0);
> +    }
> 
>     if (s->pb) // must be before any goto fail
>         s->flags |= AVFMT_FLAG_CUSTOM_IO;
> diff --git a/libavformat/internal.h b/libavformat/internal.h
> index ce837fefc7..7caae8b93e 100644
> --- a/libavformat/internal.h
> +++ b/libavformat/internal.h
> @@ -186,6 +186,11 @@ typedef struct FFFormatContext {
>      * Contexts and child contexts do not contain a metadata option
>      */
>     int metafree;
> +
> +    /**
> +     * options from avformat_open_input
> +     */
> +    AVDictionary *options;
> } FFFormatContext;
> 
> static av_always_inline FFFormatContext
> *ffformatcontext(AVFormatContext *s)
> diff --git a/libavformat/isom.h b/libavformat/isom.h
> index 64fb7065d5..dad049a2df 100644
> --- a/libavformat/isom.h
> +++ b/libavformat/isom.h
> @@ -326,6 +326,7 @@ typedef struct MOVContext {
>         int64_t extent_offset;
>     } *avif_info;
>     int avif_info_size;
> +    int use_stream_pb;
> } MOVContext;
> 
> int ff_mp4_read_descr_len(AVIOContext *pb);
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 29bd3103e3..0d5818b327 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -4519,6 +4519,18 @@ static int mov_read_trak(MOVContext *c,
> AVIOContext *pb, MOVAtom atom)
>                    st->index, dref->path, dref->dir, dref->filename,
>                    dref->volume, dref->nlvl_from, dref->nlvl_to);
>         }
> +    } else if (c->use_stream_pb) {
> +        FFFormatContext *const si = ffformatcontext(c->fc);
> +        AVDictionary *opts = NULL;
> +        av_dict_copy(&opts, si->options, 0);
> +        ret = c->fc->io_open(c->fc, &sc->pb, c->fc->url,
> AVIO_FLAG_READ, &opts);
> +        av_dict_free(&opts);
> +        if (ret < 0) {
> +            av_log(c->fc, AV_LOG_ERROR,
> +                "use_stream_pb, stream %d, error opening url %s.\n",
> +                st->index, c->fc->url);
> +            return ret;
> +        }
>     } else {
>         sc->pb = c->fc->pb;
>         sc->pb_is_copied = 1;
> @@ -9119,7 +9131,7 @@ static const AVOption mov_options[] = {
>     { "enable_drefs", "Enable external track support.",
> OFFSET(enable_drefs), AV_OPT_TYPE_BOOL,
>         {.i64 = 0}, 0, 1, FLAGS },
>     { "max_stts_delta", "treat offsets above this value as invalid",
> OFFSET(max_stts_delta), AV_OPT_TYPE_INT, {.i64 = UINT_MAX-48000*10 },
> 0, UINT_MAX, .flags = AV_OPT_FLAG_DECODING_PARAM },
> -
> +    { "use_stream_pb", "Each steam has its own AVIOContext.",
> OFFSET(use_stream_pb), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, FLAGS },
>     { NULL },
> };
> 
> --
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