2018-02-11 23:37 GMT+09:00 Jan Ekström <[email protected]>: > From: Masaki Tanaka <[email protected]> > > Lets one receive the proper field order from pictures coded in > field picture mode, until now forcibly set to BFF. > --- > libavcodec/mpegvideo_parser.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/libavcodec/mpegvideo_parser.c b/libavcodec/mpegvideo_parser.c > index be240b6890..3406346a8b 100644 > --- a/libavcodec/mpegvideo_parser.c > +++ b/libavcodec/mpegvideo_parser.c > @@ -41,7 +41,7 @@ static void mpegvideo_extract_headers(AVCodecParserContext > *s, > uint32_t start_code; > int frame_rate_index, ext_type, bytes_left; > int frame_rate_ext_n, frame_rate_ext_d; > - int top_field_first, repeat_first_field, progressive_frame; > + int picture_structure, top_field_first, repeat_first_field, > progressive_frame; > int horiz_size_ext, vert_size_ext, bit_rate_ext; > int did_set_size=0; > int set_dim_ret = 0; > @@ -51,6 +51,7 @@ static void mpegvideo_extract_headers(AVCodecParserContext > *s, > enum AVPixelFormat pix_fmt = AV_PIX_FMT_NONE; > //FIXME replace the crap with get_bits() > s->repeat_pict = 0; > + s->picture_structure = AV_PICTURE_STRUCTURE_UNKNOWN; > > while (buf < buf_end) { > start_code= -1; > @@ -114,6 +115,7 @@ static void mpegvideo_extract_headers(AVCodecParserContext > *s, > break; > case 0x8: /* picture coding extension */ > if (bytes_left >= 5) { > + picture_structure = buf[2] & 0x03; > top_field_first = buf[3] & (1 << 7); > repeat_first_field = buf[3] & (1 << 1); > progressive_frame = buf[4] & (1 << 7); > @@ -138,6 +140,18 @@ static void > mpegvideo_extract_headers(AVCodecParserContext > *s, > s->field_order = AV_FIELD_BB; > } else > s->field_order = AV_FIELD_PROGRESSIVE; > + > + switch (picture_structure) { > + case PICT_TOP_FIELD: > + s->picture_structure = > AV_PICTURE_STRUCTURE_TOP_FIELD; > + break; > + case PICT_BOTTOM_FIELD: > + s->picture_structure = > AV_PICTURE_STRUCTURE_BOTTOM_FIELD; > + break; > + case PICT_FRAME: > + s->picture_structure = > AV_PICTURE_STRUCTURE_FRAME; > + break; > + } >
Libavcodec handles MPEG-2 Video packet per frame but not picture, and the parser stops immediately after parsing the first slice of the picture. So, the parser returns per full frame but picture_structure says it's a field picture. This is evil and this is the reason why I hesitate to post this patch. I'm interested in how other devs consider this evil solution. I think the parser should parse the second field too if encountering a field coded picture, and treat the packet as frame coded and set field_order appropriate. > } > break; > } > -- > 2.14.3 > > _______________________________________________ > ffmpeg-devel mailing list > [email protected] > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > _______________________________________________ ffmpeg-devel mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
