Shulou(Shulou.com)06/01 Report--

This article introduces how to carry out FFmpeg H264 code stream analysis and playback, the content is very detailed, interested friends can refer to, hope to be helpful to you.

1) Analysis of h364_probe function

Function call

Avformat_open_input

S-> iformat- > read_header (s)

Function description

/ * *

Read the format header and initialize the AVFormatContext

Structure. Return 0 if OK. 'avformat_new_stream' should be

Called to create new streams.

/

Int (read_header) (struct AVFormatContext *)

Call from the read_header function to detect the stream format of h364

Code description

Static int h364_probe (AVProbeData * p)

{

Uint32_t code =-1; / / code = 0xffffffff

Int sps = 0, pps = 0, idr = 0, res = 0, sli = 0

Int i, ret

Int pps_ ids [Max _ PPS_COUNT+1] = {0}

Int sps_ ids [Max _ SPS_COUNT+1] = {0}

Unsigned pps_id, sps_id

GetBitContext gb

For (I = 0; I + 2)

Buf_size; iTunes +) {

Code = (code buf [I])

/ / separate the NAL start code 00 00 00 01 and analyze the NAL type

If ((code & 0xffffff00) = = 0x100) {

Int ref_idc = (code > > 5) & 3

Int type = code & 0x1F

Static const int8_t ref_zero [] = {

2, 0, 0, 0, 0, 1, 1, 1

-1, 1, 1, 1, 1,-1, 2, 2

2, 2, 2, 0, 2, 2, 2, 2

2, 2, 2, 2, 2, 2, 2, 2

}

If (code & 0x80) / / forbidden_bit

Return 0

If (ref_ Zero [type] = = 1 & & ref_idc)

Return 0

If (ref_ Zero [type] =-1 & &! ref_idc)

Return 0

If (ref_ Zero [type] = = 2) {

If (! (code = = 0x100 & &! p-> buf [I + 1] & &! p-> buf [I + 2]))

Res++

}

Ret = init_get_bits8 (& gb, p-> buf + I + 1, p-> buf_size-I-1)

If (ret

9U)

Return 0

Pps_id = get_ue_golomb_long (& gb)

If (pps_id > MAX_PPS_COUNT)

Return 0

If (! pps_ IDS [PPS _ id])

Break

If (type = = 1)

Sli++

Else

Idr++

Break

Case 7:

Skip_bits (& gb, 14)

If (get_bits (& gb, 2))

Return 0

Skip_bits (& gb, 8)

Sps_id = get_ue_golomb_long (& gb)

If (sps_id > MAX_SPS_COUNT)

Return 0

Sps_ IDS [SPS _ id] = 1

Sps++

Break

Case 8:

Pps_id = get_ue_golomb_long (& gb)

If (pps_id > MAX_PPS_COUNT)

Return 0

Sps_id = get_ue_golomb_long (& gb)

If (sps_id > MAX_SPS_COUNT)

Return 0

If (! sps_ ids [SPS _ id])

Break

Pps_ IDS [PPS _ id] = 1

Pps++

Break

}

}

}

Ff_tlog (NULL, "sps:%d pps:%d idr:%d sli:%d res:%d\ n", sps, pps, idr, sli, res)

If (sps & & pps & & (idr | | sli > 3) & & res < (sps + pps + idr))

Return AVPROBE_SCORE_EXTENSION + 1; / / 1 more than .mpg

Return 0

}

2) play

VLC media player does not support playing H264 data streams by default.

The version that currently uses VLC is 2.2.4Weatherwax

Operation steps

1 tools for opening the menu bar

2 Select preferences

3 there are two radio boxes in the lower left corner of the interface TAB page, which are concise and have a reset parameter next to them.

4 Click all

5 Click the input / edit × × menu, click on the demultiplexer in the drop-down list, but do not need to expand the drop-down list of the demultiplexer

6 in the upper right corner, select H264 video demultiplexer in the demultiplexing module

On how to carry out FFmpeg H264 stream analysis and playback is shared here, I hope the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.